Plurality of autonomous mobile robots and controlling method for the same

ABSTRACT

A plurality of autonomous mobile robots includes a first mobile robot having a first module for transmitting and receiving an Ultra-Wideband (UWB) signal, and a second mobile robot having a second module for transmitting and receiving the UWB signal. The second mobile robot follows the first mobile robot using the UWB signal.

CROSS-REFERENCE TO RELATED APPLICATION

Pursuant to 35 U.S.C. § 119(a), this application claims the benefit ofan earlier filing date of and the right of priority to KoreanApplication No. 10-2018-0051976, filed on May 4, 2018, and KoreanApplication No. 10-2019-0019452, filed on Feb. 19, 2019, the contents ofwhich are incorporated by reference herein in their entireties.

BACKGROUND ART Field of the Invention

The present invention relates to a plurality of autonomous mobilerobots.

Background of the Related Art

Generally, a mobile robot is a device that automatically performs apredetermined operation while traveling by itself in a predeterminedarea without a user's operation. The mobile robot senses obstacleslocated in the area and performs its operations by moving close to oraway from such obstacles.

Such a mobile robot may include a robot cleaner that performs cleaningwhile traveling in an area.

The robot cleaner is a cleaner that performs cleaning while traveling byitself without a user's operation.

In this manner, with the development of such mobile robots performingcleaning while traveling by themselves without users' operations,necessity to make a plurality of mobile robots perform cleaning in acollaborating manner without users' operations is emerging as aninterest.

The prior art document WO2017-036532 discloses a method in which amaster robot cleaner (hereinafter, referred to as a master robot)controls at least one slave robot cleaner (hereinafter, referred to as aslave robot).

The prior art document discloses a configuration in which the masterrobot detects adjacent obstacles by using an obstacle detection deviceand determines its position related to the slave robot using positiondata derived from the obstacle detection device.

In addition, the prior art discloses a configuration in which the masterrobot and the slave robot perform communication with each other via aserver using wireless local area network (WLAN) technology.

According to the prior art document, the master robot can determine theposition of the slave robot but the slave robot cannot determine theposition of the master robot.

Further, in order for the slave robot to determine (decide) the positionof the master robot using the configuration disclosed in the prior artdocument, the master robot must transmit relative position informationregarding the slave robot determined by the master robot to the slaverobot through a server.

However, the prior art fails to disclose such a configuration in whichthe master robot transmits relative position information to the slaverobot via the server.

In addition, even if it is assumed that the master robot transmitsrelative position information, the master robot and the slave robotshould perform communication only through the server. Accordingly, suchcommunication with the server may be disconnected when the master robotor the slave robot is located at a place where it is difficult tocommunicate with the server.

In this case, since the slave robot does not receive the relativeposition information from the server, the slave robot has difficultydeciding (determining) the relative position of the master robot, whichcauses a problem in that seamless follow-up control of the master robotand the slave robot is not performed.

In order to perform seamless follow-up control through communicationbetween a plurality of autonomous mobile robots, it is desirable todetermine whether the master robot is located at the front or at therear of the slave robot, or whether the slave robot is located at thefront or at the rear of the master robot.

However, since the prior art document merely discloses that the masterrobot transmits the relative position information to the slave robotthrough the server, it is impossible to determine whether the masterrobot is located at the front or at the rear of the slave robot, orwhether the slave robot is located at the front or at the rear of themaster robot.

SUMMARY OF THE DISCLOSURE

One aspect of the present invention is to provide mobile robots, capableof performing cleaning in an optimized manner without user'sintervention, and a control method thereof.

Another aspect of the present invention is to provide mobile robotswherein one of a plurality of mobile robots follows up another one in anoptimized manner, and a control method thereof.

Still another aspect of the present invention is to provide mobilerobots, capable of reducing costs of sensors used for follow-up controlof a plurality of mobile robots, and a control method thereof.

Still another aspect of the present invention is to provide mobilerobots, capable of recognizing relative positions of a plurality ofmobile robots, irrespective of a communication state between theplurality of mobile robots and a server, and a control method thereof.

Still another aspect of the present invention is to provide mobilerobots each of which is configured to recognize a direction that anotherrobot is located with respect to the front so as to perform seamlessfollow-up control, and a control method thereof.

To achieve the aspects and other advantages according to one embodiment,there are provided a plurality of autonomous mobile robots, including afirst mobile robot having a first module for transmitting and receivingan Ultra-Wideband (UWB) signal, and a second mobile robot having asecond module for transmitting and receiving the UWB signal, wherein thesecond mobile robot follows up the first mobile robot using the UWBsignal.

In an embodiment, the second module included in the second mobile robotmay be provided with a plurality of antennas, and a control unit of thesecond mobile robot may decide a relative position of the first mobilerobot based on the UWB signal received from the first mobile robotthrough the plurality of antennas.

In an embodiment, the second module of the second mobile robot mayinclude two antennas.

In an embodiment, the two antennas may be arranged on the same line.

In an embodiment, the two antennas may include a first antenna and asecond antenna positioned behind the first antenna, and a blockingmember for blocking the UWB signal may further be provided between thefirst antenna and the second antenna.

In an embodiment, the two antennas may be disposed at an outermost sideof a main body of the second mobile robot to have a maximum distancetherebetween on the main body.

In an embodiment, the main body of the second mobile robot may block theUWB signal.

In an embodiment, the first module may be a UWB tag, and the secondmodule may be a UWB anchor. The first mobile robot may be provided withone UWB tag and the second module may be provided with two UWB anchors.

In an embodiment, the second mobile robot may include a first UWB anchorand a second UWB anchor. The first UWB anchor may be provided with afirst antenna, a second antenna located behind the first antenna, and ablocking member provided between the first antenna and the secondantenna for blocking the UWB signal.

In an embodiment, the control unit of the second mobile robot maydetermine the relative position of the first mobile robot based on UWBsignals received through the first and second UWB anchors and anantenna, which receives the UWB signal, of the first and secondantennas.

In an embodiment, the control unit of the second mobile robot maycontrol the second module to output the UWB signal, and the control unitof the first mobile robot may output the UWB signal through the firstmodule, in response to the reception of the UWB signal.

In an embodiment, the second mobile robot may be provided with a firstUWB anchor and a second UWB anchor included in a plurality of secondmodules at different positions, and the first module included in thefirst mobile robot may include a UWB Tag. The control unit of the secondmobile robot may calculate a first distance between the first UWB anchorand the UWB tag and a second distance between the second UWB anchor andthe UWB tag, in response to reception of the UWB signal output in theUWB tag through the first and second UWB anchors.

In an embodiment, the control unit of the second mobile robot maydetermine two intersections of a first circle, wherein the first UWBanchor is a center of the first circle and the first distance is aradius of the first circle, and a second circle, wherein the second UWBanchor is a center of the second circle and the second distance is aradius of the second circle.

In an embodiment, the second mobile robot may be provided with a firstUWB anchor and a second UWB anchor corresponding to a plurality ofsecond modules. The first UWB anchor may be provided with a firstantenna, a second antenna and a blocking member and the blocking membermay be interposed between the first antenna and the second antenna toblock the UWB signal. The control unit of the second mobile robot maydecide one of two intersections extracted by the plurality of secondmodules as a relative position of the first mobile robot, based onwhether the UWB signal has been received through the first antenna ofthe first UWB anchor or through the second antenna of the first UWBanchor.

In an embodiment, the control unit of the second mobile robot may decidean intersection located at the front of the second mobile robot of thetwo intersections as the relative position of the first mobile robotwhen the UWB signal has been received through the first antenna locatedat the front of the blocking member, and decide an intersection locatedat the rear of the second mobile robot of the two intersections as therelative position of the first mobile robot when the UWB signal has beenreceived through the second antenna located at the rear of the blockingmember.

In an embodiment, the second module of the second mobile robot mayinclude three antennas.

In an embodiment, the three antennas may be arranged such that a figureformed by virtual lines connecting the three antennas is triangular.

In an embodiment, the second mobile robot may be provided with a firstUWB anchor and a second UWB anchor included in a plurality of secondmodules at different positions, and the first module included in thefirst mobile robot may include a UWB Tag. The control unit of the secondmobile robot may decide direction information regarding where the firstmobile robot is located with respect to a forward direction of thesecond mobile robot, on the basis of a phase difference of signalsoutput from the one UWB tag and received in the first UWB anchor and thesecond UWB anchor.

In an embodiment, the control unit of the second mobile robot maycalculate angle information regarding where the first mobile robot islocated with respect to a forward direction of the second mobile robotbased on a phase difference of the signals received in the first UWBanchor and the second UWB anchor, and determine direction informationregarding where the first mobile robot is located with respect to theforward direction of the second mobile robot based on the calculatedangle information.

In an embodiment, the control unit of the second mobile robot maycalculate distance information to the first mobile robot based on a timebetween when the signals are transmitted and received between the firstmodule and the second module, and determine the relative position of thefirst mobile robot based on the calculated distance information and thedirection information.

The present invention can provide a plurality of autonomous mobilerobots capable of accurately determining relative position of a firstmobile robot while reducing costs.

The present invention can provide a plurality of autonomous mobilerobots, capable of reducing cost while improving accuracy by calculatingtwo accurate intersection points using two UWB modules provided in asecond mobile robot and determining whether the first mobile robotexists in the front or rear using a plurality of antennas and a blockingmember.

The present invention can provide a plurality of autonomous mobilerobots, capable of allowing seamless follow-up by always recognizingmutual relative positions, irrespective of a communication state with aserver, owing to that the mutual relative positions can be recognizedbetween the first mobile robot and the second mobile robot.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating one embodiment of anautonomous mobile robot according to the present invention.

FIG. 2 is a planar view of the autonomous mobile robot illustrated inFIG. 1.

FIG. 3 is a lateral view of the autonomous mobile robot illustrated inFIG. 1.

FIG. 4 is a block diagram illustrating exemplary components of anautonomous mobile robot according to one embodiment of the presentinvention.

FIG. 5A is a conceptual view illustrating network communication betweena plurality of autonomous mobile robots according to one embodiment ofthe present invention, and FIG. 5B is a conceptual view illustrating anexample of the network communication of FIG. 5A.

FIG. 5C is a conceptual view illustrating follow-up traveling of aplurality of autonomous mobile robots according to one embodiment of thepresent invention.

FIGS. 6A and 6B are conceptual views illustrating a method ofdetermining relative positions of a first mobile robot and a secondmobile robot using infrared ray (IR) sensors in accordance with oneembodiment of the present invention.

FIGS. 7A and 7B are conceptual views illustrating a method ofdetermining relative positions of a first mobile robot and a secondmobile robot using UWB modules in accordance with one embodiment of thepresent invention.

FIGS. 8A, 8B, 9 and 10 are conceptual views and a flowchart illustratinga method of determining relative positions of a first mobile robot and asecond mobile robot using UWB modules according to another embodiment ofthe present invention.

FIGS. 11A, 11B, and 11C are conceptual views illustrating follow-upregistration and follow-up control between a first mobile robot and amobile device according to an alternative embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE DISCLOSURE

Hereinafter, autonomous mobile robots according to the present inventionwill be described in detail with reference to the accompanying drawings.

Hereinafter, description will be given in detail of embodimentsdisclosed herein. Technical terms used in this specification are merelyused for explaining specific embodiments, and should not be constructedto limit the scope of the technology disclosed herein.

First, the term “mobile robot” disclosed herein may be used as the samemeaning as ‘robot (for a specific function),’ ‘robot cleaner,’ ‘robotfor cleaning’ and ‘autonomous cleaner,’ and those terms will be usedequally.

“A plurality of mobile robots” disclosed herein may also be referred toas “a plurality of robot cleaners” or “a plurality of cleaners.” “Firstmobile robot” may be referred to as “first robot,” “first robotcleaner,” “first cleaner,” or “master cleaner.” Further, “second mobilerobot” may be referred to as “second robot,” “second robot cleaner,”“second cleaner,” or “slave cleaner.”

FIGS. 1 to 3 illustrate a robot cleaner as an example of a mobile robotaccording to the present invention.

FIG. 1 is a perspective view illustrating one embodiment of anautonomous mobile robot 100 according to the present invention, FIG. 2is a planar view of the autonomous mobile robot 100 illustrated in FIG.1, and FIG. 3 is a lateral view of the autonomous mobile robot 100illustrated in FIG. 1.

In this specification, a mobile robot, an autonomous mobile robot, and acleaner that performs autonomous traveling may be used in the samesense. In this specification, a plurality of autonomous mobile robotsmay include at least part of configurations illustrated in FIGS. 1 to 3.

Referring to FIGS. 1 to 3, an autonomous mobile robot 100 performs afunction of cleaning a floor while traveling on a predetermined area byitself. Cleaning the floor disclosed herein includes sucking dust andforeign materials on the floor or mopping the floor.

The autonomous mobile robot 100 may include a cleaner main body 110, acleaning unit 120, a sensing unit 130, and a dust bin 140.

The cleaner main body 110 is provided with various components inaddition to a controller or control unit (not illustrated) forcontrolling the autonomous mobile robot 100. In addition, the cleanermain body 110 is provided with a wheel unit 111 for traveling theautonomous mobile robot 100. The autonomous mobile robot 100 may bemoved or rotated forward, backward, left or right by the wheel unit 111.

Referring to FIG. 3, the wheel unit 111 includes main wheels 111 a and asub wheel 111 b.

The main wheels 111 a are provided on both sides of the cleaner mainbody 110 and configured to be rotatable in one direction or anotherdirection according to a control signal of the control unit. Each of themain wheels 111 a may be configured to be driven independently. Forexample, each main wheel 111 a may be driven by a different motor. Oreach main wheel 111 a may be driven by a plurality of different axesprovided in one motor.

The sub wheel 111 b supports the cleaner main body 110 together with themain wheels 111 a and assists the traveling of the autonomous mobilerobot 100 by the main wheels 111 a. The sub wheel 111 b may also beprovided on a cleaning unit 120 to be described later.

The control unit controls the driving of the wheel unit 111, so that theautonomous mobile robot 100 is allowed to autonomously run the floor.

Meanwhile, the cleaner main body 110 is provided with a battery (notshown) for supplying power to the autonomous mobile robot 100. Thebattery 190 may be configured to be rechargeable, and may be detachablydisposed in a bottom portion of the cleaner main body 110.

In FIG. 1, a cleaning unit 120 may be disposed in a protruding form fromone side of the cleaner main body 110, so as to suck air containing dustor mop an area. The one side may be a side where the cleaner main body110 travels in a forward direction F, that is, a front side of thecleaner main body 110.

In this drawing, the cleaning unit 120 is shown having a shapeprotruding from one side of the cleaner main body 110 to front and bothleft and right sides. Specifically, a front end portion of the cleaningunit 120 is disposed at a position spaced forward apart from the oneside of the cleaner main body 110, and left and right end portions ofthe cleaning unit 120 are disposed at positions spaced apart from theone side of the cleaner main body 110 in the right and left directions.

As the cleaner main body 110 is formed in a circular shape and bothsides of a rear end portion of the cleaning unit 120 protrude from thecleaner main body 110 to both left and right sides, empty spaces,namely, gaps may be formed between the cleaner main body 110 and thecleaning unit 120. The empty spaces are spaces between both left andright end portions of the cleaner main body 110 and both left and rightend portions of the cleaning unit 120 and each has a shape recessed intothe autonomous mobile robot 100.

If an obstacle is caught in the empty space, the autonomous mobile robot100 may be likely to be unmovable due to the obstacle. To prevent this,a cover member 129 may be disposed to cover at least part of the emptyspace.

The cover member 129 may be provided on the cleaner main body 110 or thecleaning unit 120. In an embodiment of the present invention, the covermember 129 protrude from each of both sides of the rear end portion ofthe cleaning unit 120 and covers an outer circumferential surface of thecleaner main body 110.

The cover member 129 is disposed to fill at least part of the emptyspace, that is, the empty space between the cleaner main body 110 andthe cleaning unit 120. This may result in realizing a structure capableof preventing an obstacle from being caught in the empty space, or toeasily escape an obstacle even if the obstacle is caught in the emptyspace.

The cover member 129 protruding from the cleaning unit 120 may besupported on the outer circumferential surface of the cleaner main body110.

The cover member 129 may be supported on a rear portion of the cleaningunit 120 if the cover member 129 protrudes from the cleaner main body110. According to this structure, when the cleaning unit 120 is impacteddue to colliding with an obstacle, a part of the impact is transferredto the cleaner main body 110 so as to be dispersed.

The cleaning unit 120 may be detachably coupled to the cleaner main body110. When the cleaning unit 120 is detached from the cleaner main body110, a mop module (not shown) may be detachably coupled to the cleanermain body 110 in place of the detached cleaning unit 120.

Accordingly, the user can mount the cleaning unit 120 on the cleanermain body 110 when the user wishes to remove dust on the floor, and maymount the mop module on the cleaner main body 110 when the user wants tomop the floor.

When the cleaning unit 120 is mounted on the cleaner main body 110, themounting may be guided by the cover member 129 described above. That is,as the cover member 129 is disposed to cover the outer circumferentialsurface of the cleaner main body 110, a relative position of thecleaning unit 120 with respect to the cleaner main body 110 may bedetermined.

The cleaning unit 120 may be provided with a castor 123. The caster 123assists the running of the autonomous mobile robot 100 and also supportsthe autonomous mobile robot 100.

The cleaner main body 110 is provided with a sensing unit 130. Asillustrated, the sensing unit 130 may be disposed on one side of thecleaner main body 110 where the cleaning unit 120 is located, that is,on a front side of the cleaner main body 110.

The sensing unit 130 may be disposed to overlap the cleaning unit 120 inan up and down direction of the cleaner main body 110. The sensing unit130 is disposed at an upper portion of the cleaning unit 120 so as todetect an obstacle or feature in front of the robot so that the cleaningunit 120 positioned at the forefront of the autonomous mobile robot 100does not hit the obstacle.

The sensing unit 130 may be configured to additionally perform anothersensing function other than the sensing function.

By way of example, the sensing unit 130 may include a camera 131 foracquiring surrounding images. The camera 131 may include a lens and animage sensor. The camera 131 may convert a surrounding image of thecleaner main body 110 into an electrical signal that can be processed bythe control unit. For example, the camera 131 may transmit an electricalsignal corresponding to an upward image to the control unit. Theelectrical signal corresponding to the upward image may be used by thecontrol unit to detect the position of the cleaner main body 110.

In addition, the sensing unit 130 may detect obstacles such as walls,furniture, and cliffs on a traveling surface or a traveling path of theautonomous mobile robot 100. Also, the sensing unit 130 may sensepresence of a docking device that performs battery charging. Also, thesensing unit 130 may detect ceiling information so as to map a travelingarea or a cleaning area of the autonomous mobile robot 100.

The cleaner main body 110 is provided with a dust container 140detachably coupled thereto for separating and collecting dust fromsucked air.

The dust container 140 is provided with a dust container cover 150 whichcovers the dust container 140. In an embodiment, the dust containercover 150 may be coupled to the cleaner main body 110 by a hinge to berotatable. The dust container cover 150 may be fixed to the dustcontainer 140 or the cleaner main body 110 to keep covering an uppersurface of the dust container 140. The dust container 140 may beprevented from being separated from the cleaner main body 110 by thedust container cover 150 when the dust container cover 150 is disposedto cover the upper surface of the dust container 140.

A part of the dust container 140 may be accommodated in a dust containeraccommodating portion and another part of the dust container 140protrudes toward the rear of the cleaner main body 110 (i.e., a reversedirection R opposite to a forward direction F).

The dust container 140 is provided with an inlet through which aircontaining dust is introduced and an outlet through which air separatedfrom dust is discharged. The inlet and the outlet communicate with eachother through an opening formed through an inner wall of the cleanermain body 110 when the dust container 140 is mounted on the cleaner mainbody 110. Thus, an intake passage and an exhaust passage inside thecleaner main body 110 may be formed.

According to such connection, air containing dust introduced through thecleaning unit 120 flows into the dust container 140 through the intakepassage inside the cleaner main body 110 and the air is separated fromthe dust while passing through a filter and cyclone of the dustcontainer 140. The separated dust is collected in the dust container140, and the air is discharged from the dust container 140 and flowsalong the exhaust passage inside the cleaner main body 110 so as to beexternally exhausted through an exhaust port.

Hereinafter, an embodiment related to the components of the autonomousmobile robot 100 will be described with reference to FIG. 4.

An autonomous mobile robot 100 or a mobile robot according to anembodiment of the present invention may include a communication unit1100, an input unit 1200, a traveling unit 1300, a sensing unit 1400, anoutput unit 1500, a power supply unit 1600, a memory 1700, a controlunit 1800, and a cleaning unit 1900, or a combination thereof.

At this time, those components shown in FIG. 4 are not essential, and anautonomous mobile robot having greater or fewer components can beimplemented. Also, as described above, each of a plurality of autonomousmobile robots described in the present invention may equally includeonly some of components to be described below. That is, a plurality ofautonomous mobile robots may include different components.

Hereinafter, each component will be described.

First, the power supply unit 1600 includes a battery that isrechargeable by an external commercial power supply, and supplies powerto the mobile robot. The power supply unit 1600 supplies driving forceto each of the components included in the mobile robot to supplyoperating power required for the mobile robot to travel or perform aspecific function.

At this time, the control unit may detect a remaining amount of power(or remaining power level or battery level) of the battery. The controlunit may control the mobile robot to move to a charging base connectedto the external commercial power supply when the remaining power isinsufficient, so that the battery can be charged by receiving chargingcurrent from the charging base. The battery may be connected to abattery sensing portion so that a remaining power level and a chargingstate can be transmitted to the control unit 1800. The output unit 1500may display the remaining battery level under the control of the controlunit.

The battery may be located in a bottom portion of a center of theautonomous mobile robot, or may be located in either the left or rightside. In the latter case, the mobile robot may further include a balanceweight to eliminate weight bias of the battery.

The control unit 1800 performs processing of information based on anartificial intelligence (AI) technology and may include one or moremodules that perform at least one of learning of information, inferenceof information, perception of information, and processing of naturallanguage.

The control unit 1800 may use a machine running technology to perform atleast one of learning, inferring and processing a large amount ofinformation (big data), such as information stored in the cleaner,environmental information around a mobile terminal, information storedin an external storage capable of performing communication, and thelike. The control unit 1800 may control the cleaner to predict (orinfer) at least one executable operation and execute an operation havingthe highest feasibility among the predicted at least one operation, byusing the information learned using the machine running technology.

Machine learning technology is a technology that collects and learns alarge amount of information based on at least one algorithm, and judgesand predicts information based on the learned information. The learningof information is an operation that grasps characteristics, rules, andjudgment criteria of information, quantifies relationship betweeninformation and information, and predicts new data using a quantifiedpattern.

The at least one algorithm used by the machine learning technology maybe a statistical based algorithm, for example, a decision tree that usesa tree structure type as a prediction model, an artificial neuralnetwork copying neural network architecture and functions, geneticprogramming based on biological evolutionary algorithms, clustering todistribute observed examples into subsets of clusters, Monte Carlomethod to compute function values through randomly extracted randomnumbers from probability, or the like.

As a field of machine learning technology, deep learning is a techniquethat performs at least one of learning, judging, and processing ofinformation using an Artificial Neural Network (ANN) or a Deep NeuronNetwork (DNN) algorithm. Such DNN may have an architecture in whichlayers are connected to transfer data between the layers. This deeplearning technology may allow learning of a large amount of informationthrough the DNN using a graphic processing unit (GPU) optimized forparallel computing.

The control unit 1800 may use training data stored in an external serveror memory, and may include a learning engine mounted to detectcharacteristics for recognizing a predetermined object. At this time,the characteristics for recognizing the object may include a size, shapeand shade of the object.

Specifically, when the control unit 1800 inputs a part of imagesacquired through the camera provided on the cleaner into the learningengine, the learning engine may recognize at least one object ororganism included in the input images.

When the learning engine is applied to traveling of the cleaner, thecontrol unit 1800 can recognize whether or not an obstacle such as achair leg, a fan, and a specific shape of balcony gap, which obstructthe running of the cleaner, exists around the cleaner. This may resultin enhancing efficiency and reliability of the traveling of the cleaner.

On the other hand, the learning engine may be mounted on the controlunit 1800 or on an external server. When the learning engine is mountedon an external server, the control unit 1800 may control thecommunication unit 1100 to transmit at least one image to be analyzed,to the external server.

The external server may input the image transmitted from the cleanerinto the learning engine and thus recognize at least one object ororganism included in the image. In addition, the external server maytransmit information related to the recognition result back to thecleaner. In this case, the information related to the recognition resultmay include information related to the number of objects included in theimage to be analyzed and a name of each object.

On the other hand, the traveling unit 1300 may include a motor, andoperate the motor to bidirectionally rotate left and right main wheels,so that the main body can rotate or move. At this time, the left andright main wheels may be independently moved. The traveling unit 1300may advance the main body of the mobile robot forward, backward, left,right, curvedly, or in place.

On the other hand, the input unit 1200 receives various control commandsfor the autonomous mobile robot from the user. The input unit 1200 mayinclude one or more buttons, for example, the input unit 1200 mayinclude an OK button, a setting button, and the like. The OK button is abutton for receiving a command for confirming detection information,obstacle information, position information, and map information from theuser, and the setting button is a button for receiving a command forsetting those information from the user.

In addition, the input unit 1200 may include an input reset button forcanceling a previous user input and receiving a new user input, a deletebutton for deleting a preset user input, a button for setting orchanging an operation mode, a button for receiving an input to return tothe charging base.

In addition, the input unit 1200 may be implemented as a hard key, asoft key, a touch pad, or the like and may be disposed on a top of themobile robot. For example, the input unit 1200 may implement a form of atouch screen together with the output unit 1500.

On the other hand, the output unit 1500 may be installed on a top of themobile robot. Of course, an installation location and an installationtype may vary. For example, the output unit 1500 may display a batterylevel state, a traveling mode or manner, or the like on a screen.

The output unit 1500 may output internal status information of themobile robot detected by the sensing unit 1400, for example, a currentstatus of each component included in the mobile robot. The output unit1500 may also display external status information detected by thesensing unit 1400, obstacle information, position information, mapinformation, and the like on the screen. The output unit 1500 may beconfigured as one device of a light emitting diode (LED), a liquidcrystal display (LCD), a plasma display panel, and an organic lightemitting diode (OLED).

The output unit 1500 may further include an audio output module foraudibly outputting information related to an operation of the mobilerobot executed by the control unit 1800 or an operation result. Forexample, the output unit 1500 may output warning sound to the outside inresponse to a warning signal generated by the control unit 1800.

In this case, the audio output module (not shown) may be means, such asa beeper, a speaker or the like for outputting sounds, and the outputunit 1500 may output sounds to the outside through the audio outputmodule using audio data or message data having a predetermined patternstored in the memory 1700.

Accordingly, the mobile robot according to an embodiment of the presentinvention can output environmental information related to a travelingarea through the output unit 1500 or output the same in an audiblemanner. According to another embodiment, the mobile robot may transmitmap information or environmental information to a terminal devicethrough the communication unit 1100 so that the terminal device outputsa screen or sounds to be output through the output unit 1500.

The memory 1700 stores a control program for controlling or driving theautonomous mobile robot and data corresponding thereto. The memory 1700may store audio information, image information, obstacle information,position information, map information, and the like. Also, the memory1700 may store information related to a traveling pattern.

The memory 1700 is configured mainly as a nonvolatile memory. Here, thenon-volatile memory (NVM, NVRAM) is a storage device that cancontinuously store information even when power is not supplied. Examplesof the storage device include a ROM, a flash memory, a magnetic computerstorage device (e.g., a hard disk, a diskette drive, a magnetic tape),an optical disk drive, a magnetic RAM, a PRAM, and the like.

On the other hand, the sensing unit 1400 may include at least one of anexternal signal sensor, a front sensor, a cliff sensor, atwo-dimensional (2D) camera sensor, and a three-dimensional (3D) camerasensor.

The external signal sensor or external signal detection sensor may sensean external signal of a mobile robot. The external signal sensor may be,for example, an infrared ray (IR) sensor, an ultrasonic sensor, a radiofrequency (RF) sensor, or the like.

The mobile robot may detect a position and direction of the chargingbase by receiving a guidance signal generated by the charging base usingthe external signal sensor. At this time, the charging base may transmita guidance signal indicating a direction and distance so that the mobilerobot can return thereto. That is, the mobile robot may determine acurrent position and set a moving direction by receiving a signaltransmitted from the charging base, thereby returning to the chargingbase.

On the other hand, the front sensors or front detection sensors may beinstalled at a predetermined distance on the front of the mobile robot,specifically, along a circumferential surface of a side surface of themobile robot. The front sensor is located on at least one side surfaceof the mobile robot to detect an obstacle in front of the mobile robot.The front sensor may detect an object, especially an obstacle, existingin a moving direction of the mobile robot and transmit detectioninformation to the control unit 1800. That is, the front sensor maydetect protrusions on the moving path of the mobile robot, householdappliances, furniture, walls, wall corners, and the like, and transmitthe information to the control unit 1800.

For example, the frontal sensor may be an infrared ray (IR) sensor, anultrasonic sensor, an RF sensor, a geomagnetic sensor, or the like, andthe mobile robot may use one type of sensor as the front sensor or twoor more types of sensors if necessary.

An ultrasonic sensor, for example, may generally be used to detect aremote obstacle. The ultrasonic sensor may be provided with atransmitter and a receiver. The control unit 1800 may determine presenceor non-presence of an obstacle according to whether ultrasonic wavesradiated from the transmitter are reflected by an obstacle or the likeand then received by the receiver, and calculate a distance from theobstacle using an ultrasonic wave radiation time and an ultrasonic wavereception time.

Also, the control unit 1800 may detect information related to a size ofan obstacle by comparing ultrasonic waves radiated from the transmitterwith ultrasonic waves received by the receiver. For example, the controlunit 1800 may determine that the obstacle is larger in size when moreultrasonic waves are received in the receiver.

In one embodiment, a plurality (e.g., five) of ultrasonic sensors may beinstalled on side surfaces of the mobile robot at the front side alongan outer circumferential surface. At this time, the ultrasonic sensorsmay preferably be installed on the front surface of the mobile robot ina manner that the transmitter and the receiver are alternately arranged.

That is, the transmitters may be disposed at right and left sides withbeing spaced apart from a front center of the main body or onetransmitter or at least two transmitters may be disposed between thereceivers so as to form a reception area of an ultrasonic signalreflected from an obstacle or the like. With this arrangement, thereception area can increase while reducing the number of sensors. Aradiation angle of ultrasonic waves may be maintained in a range ofavoiding an affection to different signals so as to prevent a crosstalk.Also, receiving sensitivity of the receivers may be set differently.

In addition, the ultrasonic sensor may be installed upward by apredetermined angle so that the ultrasonic waves emitted from theultrasonic sensor are output upward. In this instance, the ultrasonicsensor may further include a predetermined blocking member to preventthe ultrasonic waves from being radiated downward.

On the other hand, as described above, the front sensor may beimplemented by using two or more types of sensors together, and thus thefront sensor may use any one of an IR sensor, an ultrasonic sensor, anRF sensor and the like.

For example, the front sensor may include an IR sensor as anothersensor, in addition to the ultrasonic sensor.

The IR sensor may be installed on an outer circumferential surface ofthe mobile robot together with the ultrasonic sensor. The IR sensor mayalso detect an obstacle existing on a front or side of the mobile robotand transmit obstacle information to the control unit 1800. That is, theIR sensor senses a protrusion, a household fixture, furniture, a wall, awall edge, and the like, existing on the moving path of the mobilerobot, and transmits detection information to the control unit 1800.Therefore, the mobile robot can move within a specific area withoutcollision with an obstacle.

On the other hand, a cliff sensor (or cliff detection sensor) may detectan obstacle on the floor supporting the main body of the mobile robot bymainly using various types of optical sensors.

That is, the cliff sensor may also be installed on a rear surface of themobile robot on the floor, but may be installed on a different positiondepending on a type of the mobile robot. The cliff sensor is located onthe rear surface of the mobile robot and detects an obstacle on thefloor. The cliff sensor may be an IR sensor, an ultrasonic sensor, an RFsensor, a Position Sensitive Detector (PSD) sensor, and the like, whichinclude a transmitter and a receiver, similar to the obstacle detectionsensor.

For example, one of the cliff sensors may be installed on the front ofthe mobile robot, and two other cliff sensors may be installedrelatively behind.

For example, the cliff sensor may be a PSD sensor, but may alternativelybe configured by a plurality of different kinds of sensors.

The PSD sensor detects a short/long distance location of incident lightat one p-n junction using semiconductor surface resistance. The PSDsensor includes a one-dimensional PSD sensor that detects light only inone axial direction, and a two-dimensional PSD sensor that detects alight position on a plane. Both of the PSD sensors may have a pinphotodiode structure. As a type of IR sensor, the PSD sensor usesinfrared rays. The PSD sensor emits infrared ray, and measures adistance by calculating an angle of the infrared ray reflected andreturned from an obstacle. That is, the PSD sensor calculates a distancefrom the obstacle by using the triangulation method.

The PSD sensor includes a light emitter that emits infrared rays to anobstacle and a light receiver that receives infrared rays that arereflected and returned from the obstacle, and is configured typically asa module type. When an obstacle is detected by using the PSD sensor, astable measurement value may be obtained irrespective of reflectivityand color difference of the obstacle.

The control unit 1800 may measure an infrared ray angle between a lightsignal of infrared ray emitted by the cliff detection sensor toward theground and a reflection signal reflected and received from an obstacle,so as to detect a cliff and analyze a depth of the cliff.

Meanwhile, the control unit 1800 may determine whether to pass a cliffor not according to a ground state of the detected cliff by using thecliff detection sensor, and decide whether to pass the cliff or notaccording to the determination result. For example, the control unit1800 determines presence or non-presence of a cliff and a depth of thecliff through the cliff sensor, and then allows the mobile robot to passthrough the cliff only when a reflection signal is detected through thecliff sensor.

As another example, the control unit 1800 may also determine lifting ofthe mobile robot using the cliff sensor.

On the other hand, the two-dimensional camera sensor is provided on onesurface of the mobile robot to acquire image information related to thesurroundings of the main body during movement.

An optical flow sensor converts a lower image input from an image sensorprovided in the sensor to generate image data of a predetermined format.The generated image data may be stored in the memory 1700.

Also, at least one light source may be installed adjacent to the opticalflow sensor. The at least one light source emits light to apredetermined area of the floor, which is captured by the image sensor.That is, while the mobile robot moves in a specific area along the floorsurface, a certain distance is maintained between the image sensor andthe floor surface when the floor surface is flat. On the other hand,when the mobile robot moves on a floor surface which is not flat, theimage sensor and the floor surface are spaced apart from each other by apredetermined distance due to an unevenness and an obstacle on the floorsurface. At this time, the at least one light source may be controlledby the control unit 1800 to adjust an amount of light to be emitted. Thelight source may be a light emitting device, for example, a lightemitting diode (LED), which is capable of adjusting an amount of light.

The control unit 1800 may detect a position of the mobile robotirrespective of slippage of the mobile robot, using the optical flowsensor. The control unit 1800 may compare and analyze image datacaptured by the optical flow sensor according to time to calculate amoving distance and a moving direction, and calculate a position of themobile robot based on the calculated moving distance and movingdirection. By using the image information regarding the lower side ofthe mobile robot captured by the optical flow sensor, the control unit1800 may perform correction that is robust against slippage with respectto the position of the mobile robot calculated by another member.

The three-dimensional (3D) camera sensor may be attached to one surfaceor a part of the main body of the mobile robot to generate 3D coordinateinformation related to surroundings of the main body.

That is, the 3D camera sensor may be a 3D depth camera that calculates aremote/near distance between the mobile robot and an object to becaptured.

Specifically, the 3D camera sensor may capture 2D images related tosurroundings of the main body, and generate a plurality of 3D coordinateinformation corresponding to the captured 2D images.

In one embodiment, the 3D camera sensor may be configured in astereoscopic vision type which includes two or more cameras foracquiring 2D images, and merges at least two images acquired by the twoor more cameras to generate a 3D coordinate information.

Specifically, the 3D camera sensor according to the embodiment mayinclude a first pattern irradiating portion for downwardly irradiatinglight of a first pattern toward the front of the main body, a secondpattern irradiating portion for upwardly irradiating light of a secondpattern toward the front of the main body, and an image acquiringportion for acquiring a front image of the main body. Thus, the imageacquiring portion may acquire an image of an area where the light of thefirst pattern and the light of the second pattern are incident.

In another embodiment, the 3D camera sensor may include an infraredpattern irradiating portion for irradiating an infrared pattern, inaddition to a single camera, and capture a shape that the infraredpattern irradiated from the infrared pattern irradiating portion isprojected onto an object to be captured, thereby measuring a distancebetween the 3D camera sensor and the object to be captured. The 3Dcamera sensor may be an IR type 3D camera sensor.

In another embodiment, the 3D camera sensor may include a light emittingportion for emitting light, in addition to a single camera. The 3Dcamera sensor may receive a part of laser light (or laser beam), whichis emitted from the light emitting portion and reflected from an objectto be captured, and analyze the received light, thereby measuring adistance between the 3D camera sensor and the object to be captured. The3D camera sensor may be a time-of-flight (TOF) type 3D camera sensor.

Specifically, the laser of the 3D camera sensor is configured toirradiate a laser beam extending in at least one direction. In oneexample, the 3D camera sensor may be provided with first and secondlasers. The first laser irradiates linear laser beams intersecting eachother, and the second laser irradiates single linear laser beam.According to this, the lowermost laser is used to detect an obstacle ona bottom, the uppermost laser is used to detect an obstacle on a top,and an intermediate laser between the lowermost laser and the uppermostlaser is used to detect an obstacle at a middle portion.

On the other hand, the communication unit 1100 is connected to aterminal device and/or another device (also referred to as “homeappliance” herein) through one of wired, wireless and satellitecommunication methods, so as to transmit and receive signals and data.

The communication unit 1100 may transmit and receive data with anotherdevice located in a specific area. In this case, the another device maybe any device if it can transmit and receive data through a network. Forexample, the another device may be an air conditioner, a heating device,an air purifier, a lamp, a TV, a vehicle, and the like. The anotherdevice may also be a device for controlling a door, a window, a watersupply valve, a gas valve, or the like. The another device may also be asensor for detecting temperature, humidity, air pressure, gas, or thelike.

Further, the communication unit 1100 may communicate with anotherautonomous mobile robot 100 located in a specific area or within apredetermined range.

Referring to FIGS. 5A and 5B, a first autonomous mobile robot 100 a anda second autonomous mobile robot 100 b may exchange data with each otherthrough a network communication 50. In addition, the first autonomousmobile robot 100 a and/or the second autonomous mobile robot 100 b mayperform a cleaning related operation or a corresponding operation by acontrol command received from a terminal 300 through the networkcommunication 50 or other communication.

That is, although not shown, the plurality of autonomous mobile robots100 a and 100 b may perform communication with the terminal 300 througha first network communication and perform communication with each otherthrough a second network communication.

Here, the network communication 50 may refer to short-rangecommunication using at least one of wireless communication technologies,such as a wireless LAN (WLAN), a wireless personal area network (WPAN),a wireless fidelity (Wi-Fi) Wi-Fi direct, Digital Living NetworkAlliance (DLNA), Wireless Broadband (WiBro), World Interoperability forMicrowave Access (WiMAX), Zigbee, Z-wave, Blue-Tooth, Radio FrequencyIdentification (RFID), Infrared Data Association (IrDA), Ultrawide-Band(UWB), Wireless Universal Serial Bus (USB), and the like.

The network communication 50 may vary depending on a communication modeof the autonomous mobile robots desired to communicate with each other.

In FIG. 5A, the first autonomous mobile robot 100 a and/or the secondautonomous mobile robot 100 b may provide information sensed by therespective sensing units thereof to the terminal 300 through the networkcommunication 50. The terminal 300 may also transmit a control commandgenerated based on the received information to the first autonomousmobile robot 100 a and/or the second autonomous mobile robot 100 b viathe network communication 50.

In FIG. 5A, the communication unit of the first autonomous mobile robot100 a and the communication unit of the second autonomous mobile robot100 b may also directly communicate with each other or indirectlycommunicate with each other via another router (not shown), to recognizeinformation related to a traveling state and positions of counterparts.

In one example, the second autonomous mobile robot 100 b may perform atraveling operation and a cleaning operation according to a controlcommand received from the first autonomous mobile robot 100 a. In thiscase, it may be said that the first autonomous mobile robot 100 aoperates as a master cleaner and the second autonomous mobile robot 100b operates as a slave cleaner. Alternatively, it can be said that thesecond autonomous mobile robot 100 b follows up the first autonomousmobile robot 100 a. In some cases, it may also be said that the firstautonomous mobile robot 100 a and the second autonomous mobile robot 100b collaborate with each other.

Hereinafter, a system including a plurality of cleaners 100 a and 100 bperforming autonomous traveling according to an embodiment of thepresent invention will be described with reference to FIG. 5B.

As illustrated in FIG. 5B, a cleaning system according to an embodimentof the present invention may include a plurality of cleaners 100 a and100 b performing autonomous traveling, a network 50, a server 500, and aplurality of terminals 300 a and 300 b.

The plurality of cleaners 100 a and 100 b, the network 50 and at leastone terminal 300 a may be disposed in a building 10 while anotherterminal 300 b and the server 500 may be located outside the building10.

The plurality of cleaners 100 a and 100 b are cleaners that performcleaning while traveling by themselves, and may perform autonomoustraveling and autonomous cleaning. Each of the plurality of cleaners 100a and 100 b may include a communication unit 1100, in addition to thetraveling function and the cleaning function.

The plurality of cleaners 100 a and 100 b, the server 500 and theplurality of terminals 300 a and 300 b may be connected together throughthe network 50 to exchange data. To this end, although not shown, awireless router such as an access point (AP) device and the like mayfurther be provided. In this case, the terminal 300 a located in thebuilding (internal network) 10 may access at least one of the pluralityof cleaners 100 a and 100 b through the AP device so as to performmonitoring, remote control and the like with respect to the cleaner.Also, the terminal 300 b located in an external network may access atleast one of the plurality of cleaners 100 a and 100 b through the APdevice, to perform monitoring, remote control and the like with respectto the cleaner.

The server 500 may be wirelessly connected directly through the terminal300 b. Alternatively, the server 500 may be connected to at least one ofthe plurality of cleaners 100 a and 100 b without passing through themobile terminal 300 b.

The server 500 may include a programmable processor and may includevarious algorithms. By way of example, the server 500 may be providedwith algorithms related to performing machine learning and/or datamining. As an example, the server 500 may include a speech recognitionalgorithm. In this case, when receiving voice data, the received voicedata may be output by being converted into data in a text format.

The server 500 may store firmware information, operation information(course information and the like) related to the plurality of cleaners100 a and 100 b, and may register product information regarding theplurality of cleaners 100 a and 100 b. For example, the server 500 maybe a server operated by a cleaner manufacturer or a server operated byan opened application store operator.

In another example, the server 500 may be a home server that is providedin the internal network 10 and stores status information regarding thehome appliances or stores contents shared by the home appliances. If theserver 500 is a home server, information related to foreign substances,for example, foreign substance images and the like may be stored.

Meanwhile, the plurality of cleaners 100 a and 100 b may be directlyconnected to each other wirelessly via Zigbee, Z-wave, Blue-Tooth,Ultra-wide band (UWB), and the like. In this case, the plurality ofcleaners 100 a and 100 b may exchange position information and travelinginformation with each other.

At this time, any one of the plurality of cleaners 100 a and 100 b maybe a master cleaner 100 a and another may be a slave cleaner 100 b.

In this case, the first mobile robot 100 a may control traveling andcleaning of the second mobile robot 100 b. In addition, the secondmobile robot 100 b may perform traveling and cleaning while following upthe first mobile robot 100 a. Here, the operation or action that thesecond mobile robot 100 b follows up the first mobile robot 100 a refersto that the second mobile robot 100 b performs traveling and cleaningwhile following up the first mobile robot 100 a with maintaining aproper distance from the first mobile robot 100 a.

Referring to FIG. 5C, the first mobile robot 100 a controls the secondmobile robot 100 b such that the second mobile robot 100 b follows upthe first mobile robot 100 a.

For this purpose, the first mobile robot 100 a and the second mobilerobot 100 b should exist in a specific area where they can communicatewith each other, and the second mobile robot 100 b should recognize atleast a relative position of the first mobile robot 100 a.

For example, the communication unit of the first mobile robot 100 a andthe communication unit of the second mobile robot 100 b exchange IRsignals, ultrasonic signals, carrier frequencies, impulse signals, andthe like, and analyze them through triangulation, so as to calculatemovement displacements of the first mobile robot 100 a and the secondmobile robot 100 b, thereby recognizing relative positions of the firstmobile robot 100 a and the second mobile robot 100 b. However, thepresent invention is not limited to this method, and one of the variouswireless communication technologies described above may be used torecognize the relative positions of the first mobile robot 100 a and thesecond mobile robot 100 b through triangulation or the like.

When the first mobile robot 100 a recognizes the relative position withthe second mobile robot 100 b, the second mobile robot 100 b may becontrolled based on map information stored in the first mobile robot 100a or map information stored in the server, the terminal or the like. Inaddition, the second mobile robot 100 b may share obstacle informationsensed by the first mobile robot 100 a. The second mobile robot 100 bmay perform an operation based on a control command (for example, acontrol command related to a traveling direction, a traveling speed, astop, etc.) received from the first mobile robot 100 a.

Specifically, the second mobile robot 100 b performs cleaning whiletraveling along a traveling path of the first mobile robot 100 a.However, the traveling directions of the first mobile robot 100 a andthe second mobile robot 100 b do not always coincide with each other.For example, when the first mobile robot 100 a moves or rotatesup/down/right/left, the second mobile robot 100 b may move or rotateup/down/right/left after a predetermined time, and thus currentadvancing directions of the first and second mobile robot 100 a and 100b may differ from each other.

Also, a traveling speed Va of the first mobile robot 100 a and atraveling speed Vb of the second mobile robot 100 b may be differentfrom each other.

The first mobile robot 100 a may control the traveling speed Vb of thesecond mobile robot 100 b to be varied in consideration of a distance atwhich the first mobile robot 100 a and the second mobile robot 100 b cancommunicate with each other. For example, if the first mobile robot 100a and the second mobile robot 100 b move away from each other by apredetermined distance or more, the first mobile robot 100 a may controlthe traveling speed Vb of the second mobile robot 100 b to be fasterthan before. On the other hand, when the first mobile robot 100 a andthe second mobile robot 100 b move close to each other by apredetermined distance or less, the first mobile robot 100 a may controlthe traveling speed Vb of the second mobile robot 100 b to be slowerthan before or control the second mobile robot 100 b to stop for apredetermined time. Accordingly, the second mobile robot 100 b canperform cleaning while continuously following up the first mobile robot100 a.

According to the present invention, the first mobile robot 100 a may beprovided with reception sensors on front and rear sides, so that thecontrol unit of the first mobile robot 100 a can recognize a receivingdirection of an optical signal received from the second mobile robot 100b by distinguishing the front and rear sides. To this end, a UWB modulemay be provided at the rear of the first mobile robot 100 a and anotherUWB module or a plurality of optical sensors may be disposed at thefront of the first mobile robot 100 a in a spacing manner. The firstmobile robot 100 a may recognize a receiving direction of an opticalsignal received from the second mobile robot 100 b and determine whetherthe second mobile robot 100 b is coming from behind it or is located atthe front of it.

The first autonomous mobile robot 100 a of the present invention may bereferred to as a first mobile robot or a first mobile robot 100 a andthe second autonomous mobile robot 100 b may be referred to as a secondmobile robot or a second mobile robot 100 b.

In this specification, the first autonomous mobile robot 100 a will bereferred to as a first mobile robot 100 a and the second autonomousmobile robot 100 b will be referred to as a second mobile robot 100 b.

In this specification, for the sake of convenience of explanation, thefirst mobile robot 100 a serves as a leading cleaner (or a mastercleaner) that travels in a direction ahead of the second mobile robot100 b, and the second mobile robot 100 b serves as a following cleaner(or a slave cleaner) that follows up the first mobile robot 100 a.

The first and second mobile robots 100 a and 100 b may perform travelingand cleaning in a following manner without user's intervention.

To this end, it is necessary that the first mobile robot 100 arecognizes the position of the second mobile robot 100 b or the secondmobile robot 100 b recognizes the position of the first mobile robot 100a. This may mean that the relative positions of the first mobile robot100 a and the second mobile robot 100 b must be determined.

The present invention can grasp the relative positions of the firstmobile robot 100 a and the second mobile robot 100 b by using variousmethods.

For example, the communication unit of the first mobile robot 100 a andthe communication unit of the second mobile robot 100 b exchange IRsignals, ultrasonic signals, carrier frequencies, impulse signals, andthe like, and recognize the relative positions of the first mobile robot100 a and the second mobile robot 100 b through triangulation using theexchanged signals.

In addition, the present invention can recognize the relative positionsof the first mobile robot 100 a and the second mobile robot 100 bthrough triangulation using one of the various wireless communicationtechnologies described above (e.g., Zigbee, Z-wave, Blue-Tooth andUltra-wide Band).

Since the triangulation method for obtaining the relative positions ofthe two devices is a general technique, a detailed description thereofwill be omitted in this specification.

FIGS. 6A and 6B are conceptual views illustrating a method ofdetermining relative positions of a first mobile robot and a secondmobile robot using IR sensors in accordance with one embodiment of thepresent invention.

The present invention may include a transmitting IR sensor and areceiving IR sensor in order to recognize the relative positions of thefirst mobile robot 100 a and the second mobile robot 100 b. For example,one transmitting IR sensor and three receiving IR sensors may be used.

For example, the transmitting IR sensor may be mounted on the firstmobile robot 100 a among the plurality of cleaners, and the receiving IRsensors may be mounted on the second mobile robot 100 b.

In this specification, the IR sensor may be a sensor capable of emittingor receiving infrared rays having a specific wavelength or a wavelengthof a specific wavelength band among infrared wavelength bands (forexample, 25 micrometers or more).

Here, the IR sensor may be referred to as first type sensors 600 a and600 b.

As shown in FIG. 6A, the first type sensors (IR sensors) may include afirst type transmitting sensor 600 a and a first type receiving sensor600 b.

The transmitting IR sensor 600 a may be provided on the first mobilerobot 100 a as the leading cleaner, for example, on an outercircumferential surface of a main body of the first mobile robot 100 a.

The receiving IR sensor 600 b may be provided on the second mobile robot100 b, which is the following cleaner.

As illustrated in FIG. 6A, the receiving IR sensor 600 b may be providedin plural.

For example, the receiving infrared sensors 600 b may include a firstreceiving IR sensor 610 b-1, a second receiving IR sensor 610 b-2, and athird receiving IR sensor 610-b. The first to third receiving IR sensors610 b-1, 610 b-2, and 610 b-3 may be mounted on the outercircumferential surface of the main body of the second mobile robot 100b at different positions.

In this case, the first to third receiving IR sensors 610 b-1, 610 b-2,and 610 b-3 may be spaced apart from one another on the outercircumferential surface of the main body of the second mobile robot 100b.

On the other hand, the control unit of the second mobile robot 100 b mayreceive laser light or laser beam, which is output from the transmittingIR sensor 600 a provided on the first mobile robot 100 a, through thereceiving IR sensor 600 b.

At this time, the control unit of the second mobile robot 100 b maymeasure intensities of laser beams received in the first to thirdreceiving IR sensors 610 b-1, 610 b-2, and 610 b-3 included in thereceiving IR sensor 600 b.

The control unit of the second mobile robot 100 b, as illustrated inFIG. 6B, may apply triangulation based on the intensities of the laserbeams measured in the first to third receiving IR sensors 610 b-1, 610b-2, 610 b-3.

Brief description of triangulation using intensity of laser light willbe given. The control unit of the second mobile robot 100 b maycalculate a first distance D1 from the first receiving IR sensor 610 b-1based on intensity of laser light received in the first receiving IRsensor 610 b-1.

At this time, the first distance D1 may be decided by multiplyingintensity of laser light by scale, and the scale may be decided throughexperiments.

For example, the first distance D1 (radius) may be shortened as theintensity of the laser light is great. That is, the radius and theintensity of the laser light may be in inverse proportion.

Likewise, the control unit of the second mobile robot 100 b maycalculate a second distance D2 from the second receiving IR sensor 610b-2 based on intensity of laser light received in the second receivingIR sensor 610 b-2.

In addition, the control unit of the second mobile robot 100 b maycalculate a third distance D2 from the third receiving IR sensor 610 b-3based on intensity of laser light received in the third receiving IRsensor 610 b-3.

Afterwards, as illustrated in FIG. 6B, the control unit of the secondmobile robot 100 b may extract (calculate, decide, determine) threecircles C1, C2, and C3 respectively having radiuses of the first tothird distances D1, D2, and D3 from the receiving IR sensors which arelocated at the centers of the respective circles, and an intersection(intersection point) P of the three circles. The control unit of thesecond mobile robot may determine the intersection as the position ofthe first mobile robot (the position of the transmitting IR sensor, moreaccurately).

At this time, the first to third receiving IR sensors 610 b-1, 610 b-2,and 610 b-3 may be arranged at different positions on the second mobilerobot 100 b, and coordinates of the arranged positions may be stored inthe control unit of the mobile robot 100 b.

The first to third receiving IR sensors 610 b-1, 610 b-2, and 610 b-3may have different distances from the transmitting IR sensor 600 a ofthe first mobile robot 100 a, and thus have different intensity of laserlight output from the first type transmitting sensor 600 a.

Therefore, the control unit of the second mobile robot 100 b can decidethe first to third distances D1, D2, and D3 with respect to therespective sensors based on intensities of laser light received throughthe first to third receiving IR sensors 610 b-1, 610 b-2, and 610 b-3,and decide the intersection P of the circles C1, C2, and C3, which havethe first to third distances as radiuses, as the position of the firstmobile robot 100 a.

More specifically, the control unit of the second mobile robot 100 b maycalculate an intersection of a first circle in which the first IR sensor610 b-1 is a center point and the first distance is a radius, a secondcircle in which the second IR sensor 610 b-2 is a center point and thesecond distance is a radius, and a third circle in which the third IRsensor 610 b-3 is a center point and the third distance is a radius, asposition coordinates (spatial coordinates) of the first mobile robot.

That is, the intersection P may be formed as spatial coordinates, andthe relative positions of the first mobile robot 100 a and the secondmobile robot 100 b may be recognized by using the spatial coordinates.

With this configuration, the present invention can provide mobile robotsin which relative positions of a plurality of cleaners can be recognizedby using inexpensive IR sensors.

On the other hand, when the IR sensor is used, if an obstacle is presentbetween the first mobile robot 100 a and the second mobile robot 100 b,the reception of the laser light is interrupted, and the relativepositions of the first and second mobile robots cannot be recognizedaccurately.

To solve this problem, as illustrated in FIGS. 6A and 6B, the presentinvention can measure the relative positions of the first mobile robotand the second mobile robot by using UWB modules instead of thetransmitting/receiving IR sensors (or laser sensors).

FIGS. 7A and 7B are conceptual views illustrating a method ofdetermining relative positions of a first mobile robot and a secondmobile robot using UWB modules in accordance with one embodiment of thepresent invention.

As described above, the UWB module (or UWB sensor) may be included inthe communication units 1100 of the first mobile robot 100 a and thesecond mobile robot 100 b. In view of the fact that the UWB modules areused to sense the relative positions of the first mobile robot 100 a andthe second mobile robot 100 b, the UWB modules may be included in thesensing units 1400 of the first mobile robot 100 a and the second mobilerobot 100 b.

The first mobile robot 100 a may include a transmitting UWB module 700 afor transmitting ultra-wideband (UWB) signals. The transmitting UWBmodule may be termed as a second type transmitting sensor or a UWB tag.

The second mobile robot 100 b may include a receiving UWB module 700 bfor receiving the UWB signals output from the transmitting UWB module700 a provided in the first mobile robot 100 a. The receiving UWB modulemay be named as a second type receiving sensor or a UWB anchor.

UWB signals transmitted/received between the UWB modules may be smoothlytransmitted and received within a specific space.

Accordingly, even if an obstacle exists between the first mobile robot100 a and the second mobile robot 100 b, if the first mobile robot 100 aand the second mobile robot 100 b exist within a specific space, theycan transmit and receive the UWB signals. This may mean that accuracy isincreased.

The first mobile robot and the second mobile robot according to thepresent invention can measure time of each signal transmitted andreceived between the UWB tag and the UWB anchor to recognize a distance(spaced distance) between the first mobile robot and the second mobilerobot.

In general, the UWB tag and the UWB anchor are both UWB modules, whichmay be modules to transmit and receive UWB signals.

For example, the UWB module included in one robot 100 b for calculating(determining) a relative position of another mobile robot 100 a may bereferred to as a UWB anchor, and a UWB module included in the robot 100a whose relative position is to be recognized may be referred to as aUWB tag.

Specifically, for example, each of the plurality of mobile robots 100 aand 100 b may be provided with one UWB sensor, or the first mobile robot100 a may be provided with a single UWB sensor, and the second mobilerobot 100 b following up the first mobile robot 100 a may be providedwith a single UWB sensor and at least one antenna or provided with atleast two UWB sensors, so that the first mobile robot 100 a can measuredistances to the second mobile robot 100 b at two different time pointst1 and t2.

The UWB sensor of the first mobile robot 100 a and the UWB sensor of thesecond mobile robot 100 b radiate UWB signals to each other, and measuredistances and relative speed using Time of Arrival (ToA) or Time ofFlight (ToF) which is a time that the signals come back by beingreflected from the robots. However, the present invention is not limitedto this, and may recognize the relative positions of the plurality ofmobile robots 100 a and 100 b using a Time Difference of Arrival (TDoA)or Angle of Arrival (AoA) positioning technique.

For example, as shown in FIG. 7B, the control unit of the second mobilerobot 100 b may output a first signal (Radio message 1) at the UWBanchor of the second mobile robot.

The first signal may be received in the UWB tag of the first mobilerobot 100 a.

The control unit of the first mobile robot 100 a may output a secondsignal (Radio message 2) in response to the reception of the firstsignal.

The control unit of the second mobile robot 100 b may receive the secondsignal through the UWB anchor 700 b.

The second signal may include delay time (t_reply) information which iscalculated based on a time at which the first mobile robot 100 a hasreceived the first signal and a time at which the first mobile terminal100 a has output the second signal.

The control unit of the second mobile robot 100 b may calculate a signaltransmission time, namely, Time of Flight (ToF) between the first mobilerobot and the second mobile robot using an output time t1 of the firstsignal, a received time t2 of the second signal, and the delay timet_reply included in the second signal.

The control unit of the second mobile robot 100 b may calculate adistance between the first mobile robot 100 a and the second mobilerobot 100 b (accurately, a distance between the UWB tag and the UWBanchor) using the output time t1 of the first signal, the received timet2 of the second signal, and the delay time t_reply included in thesecond signal. Here, c in FIG. 7B denotes speed of light.

Hereinafter, description will be given of a method of determining therelative positions of the first mobile robot 100 a and the second mobilerobot 100 b using an AoA positioning technique. In order to use the AoA(Angle of Arrival) positioning technique, each of the first mobile robot100 a and the second mobile robot 100 b should be provided with onereceiver antenna or a plurality of receiver antennas. The first mobilerobot 100 a and the second mobile robot 100 b may determine theirrelative positions using a difference (or phase difference) of anglesthat the receiver antennas provided in the robots, respectively, receivesignals. To this end, each of the first mobile robot 100 a and thesecond mobile robot 100 b must be able to sense an accurate signaldirection coming from the receiver antenna array.

Since signals, for example, UWB signals, generated in the first mobilerobot 100 a and the second mobile robot 100 b, respectively, arereceived only in specific directional antennas, they can determine(recognize) received angles of the signals. Under assumption thatpositions of the receiver antennas provided in the first mobile robot100 a and the second mobile robot 100 b are known, the relativepositions of the first mobile robot 100 a and the second mobile robot100 b may be calculated based on positions and signal receivingdirections of the receiver antennas.

At this time, if one receiver antenna is installed, a 2D position may becalculated in a space of a predetermined range. On the other hand, if atleast two receiver antennas are installed, a 3D position may bedetermined. In the latter case, a distance d between the receiverantennas is used for position calculation in order to accuratelydetermine a signal receiving direction.

For example, one UWB tag may be provided in the first mobile robot 100a, and at least two UWB anchors may be provided in the second mobilerobot 100 b. At this time, the second mobile robot 100 b may receive UWBsignals transmitted from the UWB tag of the first mobile robot 100 athrough the at least two UWB anchors.

Thereafter, the second mobile robot 100 b may determine positioninformation (or angle information) where the first mobile robot 100 a islocated with reference to a forward direction of the second mobile robot100 b, by using a phase difference between the UWB signals receivedthrough the at least two UWB anchors and a distance between the at leasttwo UWB anchors.

That is, the second mobile robot of the present invention may extractdistance information between the first mobile robot and the secondmobile robot using the ToF scheme, and determine direction information(or angle information) in which the first mobile robot is located withrespect to the forward direction of the second mobile robot 100 b usingthe AoA scheme. Further, the second mobile robot may determine therelative position of the first mobile robot using the distanceinformation and the angle information.

On the other hand, as illustrated in FIG. 7A, the second mobile robot100 b may be provided with a plurality of UWB anchors (a plurality ofreceiving UWB modules).

For example, the second mobile robot 100 b may include three UWBanchors, and the three UWB anchors may include a first UWB anchor 710b-1, a second UWB anchor 710 b-2, and a third UWB anchor 710 b-3.

The present invention can calculate the relative positions (spatialcoordinates) of the first mobile robot 100 a and the second mobile robot100 b using the plurality of UWB anchors. The triangulation described inFIG. 6B will be equally/similarly applied to calculating the relativepositions of the first mobile robot and the second mobile robot usingthree UWB anchors and one UWB tag.

For example, the second mobile robot 100 b may control each of the firstto third UWB anchors 710 b-1, 710 b-2, and 710 b-3 and extract distancesbetween the first to third UWB anchors and the UWB tag 700 a provided inthe first mobile robot 100 a.

The configuration described in FIG. 7B will be equally/similarly appliedto extracting the distance between each UWB anchor provided in thesecond mobile robot 100 b and the UWB tag 700 a provided in the firstmobile robot 100 a.

For example, the control unit of the second mobile robot 100 b mayextract a first distance between the first UWB anchor 710 b-1 and theUWB tag 700 a, a second distance between the second UWB anchor 710 b-2and the UWB tag 700 a, and a third distance between the third UWB anchor710 b-3 and the UWB tag 700 a, respectively.

Afterwards, the control unit of the second mobile robot 100 b maycalculate an intersection of a first circle in which the first UWBanchor 710 b-1 is a center point and the first distance is a radius, asecond circle in which the second UWB anchor 710 b-2 is a center pointand the second distance is a radius, and a third circle in which thethird UWB anchor 710 b-3 is a center point and the third distance is aradius, as position coordinates (spatial coordinates) of the firstmobile robot.

In this manner, according to the present invention, the relativepositions (or spatial coordinates) of the first mobile robot 100 a andthe second mobile robot 100 a can be calculated in the triangulationmanner by using the one UWB tag 700 a and the three UWB anchors 710 b-1,710 b-2 and 710 b-3.

That is, when one UWB tag and one UWB anchor are used, the distancebetween the first mobile robot and the second mobile robot may beextracted, but the relative positions (i.e., spatial coordinates) maynot be extracted. Accordingly, the present invention can extract eventhe relative positions of the first mobile robot and the second mobilerobot using one UWB tag and three UWB anchors.

On the other hand, if one UWB tag and three UWB anchors are used toextract the relative positions of the first mobile robot and the secondmobile robot, the highest accuracy is obtained but cost increase occurs.

In case where the IR sensors (or laser sensors) described with referenceto FIGS. 6A and 6B are used, if an obstacle is present between the firstmobile robot and the second mobile robot, laser transmission andreception is interrupted in view of the laser characteristic.Accordingly, when only the laser sensor is used, the determination ofthe relative positions of the first mobile robot and the second mobilerobot becomes inaccurate.

In addition, when the UWB modules described with reference to FIGS. 7Aand 7B are used, the relative positions of the first mobile robot andthe second mobile robot can be accurately extracted regardless ofexistence of an obstacle between the first mobile robot and the secondmobile robot. However, there is a problem that cost increases.

Hereinafter, various embodiments of the present invention for measuringaccurate relative positions of the first mobile robot and the secondmobile robot while reducing costs will be described in more detail withreference to the accompanying drawings.

To overcome and obviate the aforementioned problems, the presentinvention can utilize a pair of IR sensors, one transmitting UWB module,and two receiving UWB modules.

FIGS. 8A, 8B, 9 and 10 are conceptual views and a flowchart illustratinga method of determining relative positions of a first mobile robot and asecond mobile robot using a UWB module according to another embodimentof the present invention.

A plurality of autonomous mobile robots according to the presentinvention may include a first mobile robot 100 a and a second mobilerobot 100 b. The first mobile robot 100 a may serve as a leading cleanerthat travels in a direction ahead of the second mobile robot 100 b, andthe second mobile robot 100 b may serve as a following cleaner thatfollows up the first mobile robot 100 a.

In order to determine relative positions of the first mobile robot andthe second mobile robot, the first mobile robot 100 a of the presentinvention may include a module (first module) for transmitting andreceiving UWB signals.

In addition, the second mobile robot 100 b may include a module (secondmodule) for transmitting and receiving the UWB signals.

The first mobile robot 100 a may include one first module and the secondmobile robot 100 b may include a plurality of second modules (e.g., twosecond modules).

In addition, the first and second modules (or the plurality of modules)for transmitting and receiving the UWB signals may be UWB modules.

The UWB module may be included in the communication unit as describedabove. With no limit to this, the UWB module may be formed as a separatemodule or sensor.

The UWB module may include a UWB tag 700 a and a UWB anchor 700 b.

The first module may include the UWB tag, and the second module mayinclude the UWB anchor. Also, the first module may be the UWB tag, andthe second module may be the UWB anchor.

For example, the UWB tag 700 a may serve as a transmitting UWB module,and the UWB anchor 700 b may serve as a receiving UWB module. However,the present invention is not limited to this, and the UWB tag may alsoreceive a UWB signal, and the UWB anchor may also output a UWB signal.

The control unit of the second mobile robot 100 b may control the secondmobile robot 100 b to follow up the first mobile robot 100 a using theUWB signals transmitted and received through the first and secondmodules.

The configuration that the second mobile robot 100 a follows the firstmobile robot 100 a may mean that the second mobile robot 100 b travelsalong substantially the same traveling path as a traveling path of themoving first mobile robot 100 a or the second mobile robot 100 b movestoward the moving first mobile robot 100 a.

In order for the second mobile robot 100 b to follow the first mobilerobot 100 a, the second mobile robot 100 b should determine or recognizethe relative position of the first mobile robot 100 a.

Hereinafter, a method of determining or recognizing the relativeposition of the first mobile robot so that the second mobile robotfollows the first mobile robot by using the UWB signals transmitted andreceived through the first and second modules will be described in moredetail.

The second module (UWB anchor) provided in the second mobile robot 100 bmay include a plurality of antennas. The control unit of the secondmobile robot 100 b may determine the relative position of the firstmobile robot 100 b based on the UWB signals received from the firstmobile robot 100 a through the plurality of antennas.

For example, the second module (UWB anchor) included in the secondmobile robot may include two antennas.

The two antennas may be arranged on the same line, and for example, thetwo antennas may be arranged on the same line to be perpendicular orhorizontal to a forward direction of the second mobile robot.

For example, the two antennas may include a first antenna and a secondantenna. The first and second antennas may be disposed to be horizontalto the forward direction of the second mobile robot (in this case, thefirst and second antennas may be arranged back and forth).

For example, the two antennas may be arranged on the same line at apredetermined interval, and may be arranged back and forth based on thefront of the second mobile robot.

For example, the two antennas may include a first antenna and a secondantenna located behind the first antenna.

However, the present invention is not limited to this, and the twoantennas may be disposed on the same line at a predetermined interval tobe arranged at right and left sides with respect to the front of thesecond mobile robot.

For example, the two antennas may include a first antenna and a secondantenna positioned at the left or right of the first antenna.

In addition, a blocking member for blocking the UWB signal may beprovided between the first antenna and the second antenna.

The plurality of antennas (for example, two antennas or three antennas)may be provided over an entire area of the second mobile robot, or maybe provided in a partial area of the second mobile robot (for example, apartial area located at the front of the second mobile robot).

On the other hand, the plurality of antennas (for example, two antennasor three antennas) may be arranged at the outermost side (end) of themain body of the second mobile robot 100 b to have a maximum distancetherebetween on the main body.

For example, when there are two antennas, if the first antenna isdisposed on the front of the main body of the second mobile robot 100 b,the second antenna may be disposed on the rear of the main body of thesecond mobile robot 100 b.

As another example, when the plurality of antennas is three, the threeantennas may be disposed at positions corresponding to vertexes of anequilateral triangle at the outermost side of the main body of thesecond mobile robot 100 b.

In this case, a blocking member may not be provided between theplurality of antennas, and the main body of the second mobile robot 100b may serve as a blocking member.

That is, the main body of the second mobile robot may block the UWBsignals or attenuate intensities of the UWB signals.

Since the UWB signal is cut off or the intensity of the UWB signal isattenuated through the main body, the control unit of the second mobilerobot 100 b can detect the relative position of the first mobile robotbased on the type of the antenna that received the UWB signal among theplurality of antennas and intensities of the UWB signals receivedthrough the plurality of antennas.

Hereinafter, description of the blocking member disposed between thefirst and second antennas will be equally/similarly applied even to acase where the first and second antennas are disposed at the outermostside of the main body to have the maximum distance therebetween on themain body.

Hereinafter, a method of determining the relative position of the firstmobile robot using a plurality of antennas of a second module providedin the second mobile robot will be described in more detail.

The second mobile robot 100 b may include a plurality of second modules.

At least one of the plurality of second modules provided in the secondmobile robot 100 b may include a plurality of antennas (for example, twoantennas or three antennas). In addition, a blocking member for blockinga UWB signal may be disposed between the plurality of antennas.

The second mobile robot 100 b may determine the relative position of thefirst mobile robot 100 a based on the UWB signal received through theplurality of second modules and an antenna receiving the UWB signal ofthe plurality of antennas.

Hereinafter, the method of determining the relative position of thefirst mobile robot using the plurality of antennas of the second moduleprovided in the second mobile robot will be described in more detail.

As illustrated in FIG. 8A, the first mobile robot 100 a may be providedwith one UWB tag 700 a (first module).

The second mobile robot 100 b may include two UWB anchors 710 b and 720b (a plurality of second modules).

The two UWB anchors 710 b and 720 b may be disposed at differentpositions of the second mobile robot 100 b and may be mounted with adistance therebetween.

Hereinafter, description will be given under assumption that the firstmodule is a UWB tag and the second module is a UWB anchor.

The second mobile robot 100 b may include a first UWB anchor 710 b and asecond UWB anchor 720 b.

At least one of the first and second UWB anchors 710 b and 720 b may beprovided with a plurality of antennas.

That is, in the present invention, both of the first and second UWBanchors may be provided with a plurality of antennas or one (e.g., thefirst UWB anchor) of the first UWB anchor and the second UWB anchor maybe provided with a plurality of antennas.

If both of the first and second UWB anchors are provided with aplurality of antennas, each of the first and second UWB anchors mayinclude a blocking member for blocking a UWB signal between theplurality of antennas.

In this specification, for convenience of explanation, it is assumedthat only the first UWB anchor 710 b is provided with a plurality ofantennas and a blocking member.

For example, the first UWB anchor 710 b may include a first antenna 731,a second antenna 732 located at the rear (R) of the first antenna 731(i.e., a second antenna disposed on the same line as the first antenna),and a blocking member 740 provided between the first antenna 731 and thesecond antenna 732 to block the UWB signal.

Here, the rear side may mean the rear (R) with respect to the secondmobile robot 100 b. However, the present invention is not limited tothis, and the second antenna may be provided at the left or right of thefirst antenna. The blocking member 740 may block the UWB signal outputfrom the UWB tag. For example, the blocking member may be formed of ametal member (or a metallic material), and may be referred to as a metalpartition wall or a radio wave transmission preventing wall.

The present invention can determine the relative positions of the firstmobile robot and the second mobile robot based on whether the UWB signaloutput from the UWB tag 700 a is received through the first antenna 731or the second antenna 732.

Hereinafter, a method of determining the relative position of the firstmobile robot using two UWB anchors and two antennas will be described inmore detail.

Referring to FIG. 9, the control unit of the second mobile robot maycontrol the UWB anchor 700 b to output a UWB signal (S902). For example,the control unit of the second mobile robot may control at least one ofthe two UWB anchors to output the UWB signal.

The UWB signal output from the UWB anchor may serve as a trigger signalfor starting a process of recognizing the relative position of the firstmobile robot.

The control unit of the first mobile robot 100 a may receive the UWBsignal through the UWB tag 700 a. The control unit of the first mobilerobot 100 a may output the UWB signal through the UWB tag, in responseto the reception of the UWB signal (S904).

The two UWB anchors provided in the second mobile robot 100 b mayinclude a first UWB anchor 710 b and a second UWB anchor 720 b. Inaddition, the second mobile robot 100 b may be provided with the firstUWB anchor 710 b and the second UWB anchor 720 b disposed at differentpositions.

The control unit of the second mobile robot 100 b may calculate a firstdistance D1 between the first UWB anchor 710 b and the UWB tag 700 a anda second distance D2 between the second UWB anchor 720 b and the UWB tag700 a, in response to the reception of the UWB signal output in the UWBtag 700 a through the first and second UWB anchors 710 b and 720 b. Thedescription given with reference to FIG. 7B will be equally/similarlyapplied to the method of calculating (measuring) the first distance D1and the second distance D2.

Afterwards, the control unit of the second mobile robot 100 b, asillustrated in FIG. 8B, may extract two intersections P1 and P2 of afirst circle C1, wherein the first UWB anchor 710 b is a center of thefirst circle C1 and the first distance D1 is a radius of the circle C1,and a second circle C2, wherein the second UWB anchor 720 b is a centerof the second circle C2, and the second distance D2 is a radius of thesecond circle C2 (S908).

In this embodiment, since only two receiving UWB modules are usedinstead of three receiving UWB modules, the triangulation method cannotbe applied. Accordingly, two coordinate values (intersection points)estimated as the relative positions of the first mobile robot aregenerated.

To solve this problem, in this embodiment, the first antenna 731disposed in the first UWB anchor 710 b or the second antenna 732disposed at the rear of the first antenna 731 and mounted at the rear ofthe blocking member may be used to determine a direction of the firstmobile robot.

The control unit of the second mobile robot 100 b may determine one ofthe two intersections as the relative position of the first mobile robotbased on whether the UWB signal has been received through the firstantenna 731 of the first UWB anchor 710 b or the second antenna 732 ofthe first UWB anchor 710 b.

To this end, the control unit of the second mobile robot 100 b maydetermine whether or not the UWB signal has been received through thefirst antenna 731 of the first UWB anchor 710 b (S910).

The reception of the UWB signal through the first antenna 731 of thefirst UWB anchor 710 b means that the UWB signal has been transmitted atthe front of the second mobile robot 100 b because the first antenna 731is located at the front side F of the blocking member 740.

Accordingly, when the UWB signal has been received through the firstantenna 731 located at the front of the blocking member 740, the controlunit of the second mobile robot may decide the intersection P1 locatedat the front of the second mobile robot 100 b of the two intersectionsP1 and P2 as the relative position of the first mobile robot 100 a(S912).

On the other hand, when the UWB signal has been received through thesecond antenna 732 located behind the blocking member 740, the controlunit of the second mobile robot may decide the intersection P2 locatedat the rear of the second mobile robot 100 b of the two intersections P1and P2 as the relative position (or spatial coordinates) of the firstmobile robot 100 a (S914).

On the other hand, when the first and second antennas are disposed atthe outermost side of the main body to have the maximum distancetherebetween on the main body (or the UWB signal is attenuated due tothe main body), the control unit of the second mobile robot 100 b maydecide the relative position of the first mobile robot based onintensities of the UWB signals received through the first and secondantennas.

In this case, the foregoing steps S902 to S908 are performed in the samemanner.

When the first antenna is disposed at the front of the main body of thesecond mobile robot 100 b and the second antenna is disposed at the rearof the main body of the second mobile robot 100 b, both the first andsecond antennas may receive the UWB signals.

At this time, intensities of the UWB signals received by the firstantenna and the second antenna are different. This is because theintensity of the UWB signal is attenuated by the main body.

If the first mobile robot is located ahead the second mobile robot,intensity of the UWB signal received by the first antenna located at thefront of the main body of the second mobile robot may be stronger thanintensity of the UWB signal received by the second antenna located atthe rear of the main body of the second mobile robot.

The control unit of the second mobile robot 100 b may determine one ofthe two intersections as the relative position of the first mobile robotbased on the intensities of the UWB signals received by the first andsecond antennas.

For example, when the intensity of the UWB signal received by the firstantenna located at the front of the main body of the second mobile robotis stronger than the intensity of the UWB signal received by the secondantenna located at the rear of the main body of the second mobile robot,the control unit of the second mobile robot 100 b may determine theintersection located at the front of the second mobile robot of the twointersections as the relative position of the first mobile robot.

As another example, when the intensity of the UWB signal received by thefirst antenna located at the front of the main body of the second mobilerobot is weaker than the intensity of the UWB signal received by thesecond antenna located at the rear of the main body of the second mobilerobot, the control unit of the second mobile robot 100 b may determinethe intersection located at the rear of the second mobile robot of thetwo intersection points as the relative position of the first mobilerobot.

The control unit of the second mobile robot 100 b may control the firstantenna 731 and the second antenna 732 in various manners to receive theUWB signal through the first antenna 731 or the second antenna 732.

For example, the control unit of the second mobile robot 100 b mayactivate at least one of the first antenna 731 and the second antenna732, in response to an output of the UWB signal through the UWB anchor700 b (i.e., a trigger signal output).

For example, the control unit of the second mobile robot 100 b mayactivate the first antenna 731 and the second antenna 732 at the sametime.

As another example, the control unit of the second mobile robot 100 bmay first activate the first antenna 731. The control unit of the secondmobile robot 100 b may then deactivate the first antenna 731 andactivate the second antenna 732 when a predetermined time elapses afterthe output of the UWB signal.

If the UWB signal is received through the first antenna 731 while thefirst antenna 731 is activated, the control unit of the second mobilerobot 100 b may maintain the second antenna 732 in a deactivated state(i.e., activation of the second antenna 732 may be omitted).

Meanwhile, the present invention can determine or recognize the relativeposition of the first mobile robot using three or more antennas.

For example, as illustrated in FIG. 10, the first mobile robot 100 a ofthe present invention may include one UWB tag 700 a (first module), andthe second mobile robot 100 b may include one UWB anchor 700 b (secondmodule).

The one UWB anchor 700 b may be provided with at least three antennas751, 752 and 753.

The control unit of the second mobile robot 100 b may determine therelative position of the first mobile robot based on the UWB signalsreceived from the first mobile robot through the plurality of antennas(at least three antennas).

The three antennas may be arranged such that a figure formed by virtuallines connecting the three antennas is triangular.

For example, two of the three antennas may be located at the front ofthe second mobile robot, and the other antenna may be disposed at therear of the second mobile robot.

That is, the first and second antennas of the three antennas aredisposed at the front with respect to the third antenna, and may bedisposed on the same line at right and left sides with respect to thefront of the second mobile robot.

In addition, the third antenna among the three antennas may be disposedbehind with respect to the first and second antennas, and may bedisposed to have the same distance from the first and second antennas.

In this case, a virtual line extending from the third antenna toward thefront of the second mobile robot may perpendicularly divide a virtualline connecting the first and second antennas.

However, the present invention is not limited thereto, and the firstantenna may be disposed at the front of the second and third antennas,and the second and third antennas may be disposed behind the firstantenna on the second line at right and left sides with respect to thefront of the second mobile robot.

In this case, a virtual line extending from the first antenna to therear of the second mobile robot may perpendicularly divide a virtualline connecting the second and third antennas.

The at least three antennas 751, 752 and 753 may be arranged atdifferent positions of the second mobile robot 100 b and may be mountedto have distances from one another.

The second mobile robot 100 b may calculate distances between the atleast three antennas 751, 752 and 753 and the UWB tag 700 a of the firstmobile robot 100 a, and decide the relative position of the first mobilerobot 100 a using triangulation.

For example, the second mobile robot 100 b may output a UWB signalthrough the first antenna 751, and receive a UWB signal from the UWB tag700 a through the first antenna 751, thereby calculating a firstdistance between the first antenna 751 and the UWB tag 700 a.

The second mobile robot 100 b may output a UWB signal through the secondantenna 752 after receiving the UWB signal through the first antenna751, and receive a UWB signal from the UWB tag 700 a through the secondantenna 752, thereby calculating a second distance between the secondantenna 752 and the UWB tag 700 a.

The second mobile robot 100 b may output a UWB signal through the thirdantenna 753 after receiving the UWB signal through the second antenna752, and receive a UWB signal from the UWB tag 700 a through the thirdantenna 753, thereby calculating a third distance between the thirdantenna 753 and the UWB tag 700 a.

The method of calculating the distances between the antennas 751, 752,and 753 and the UWB tag 700 a will be understood by the descriptiongiven with reference to FIG. 7B, so detailed description will beomitted.

In addition, the control unit of the second mobile robot 100 b maysequentially activate the first to third antennas within a predeterminedtime, thereby calculating the first to third distances.

Further, the second mobile robot 100 b may deactivate the remainingantennas while any one of the first to third antennas is activated.

For example, when the UWB signal is output and received through thefirst antenna (i.e., when the first antenna is activated), the secondmobile robot 100 b may deactivate the second antenna and the thirdantenna.

In addition, when the UWB signal is output and received through thesecond antenna (i.e., when the second antenna is activated), the secondmobile robot 100 b may deactivate the first antenna and the thirdantenna.

Similarly, when the UWB signal is output and received through the thirdantenna (i.e., when the third antenna is activated), the second mobilerobot 100 b may deactivate the first antenna and the second antenna.

Thereafter, the control unit of the second mobile robot 100 b mayextract an intersection of a first circle, wherein the first antenna isa center of the first circle and the first distance is a radius of thefirst circle, a second circle, wherein the second antenna is a center ofthe second circle and the second distance is a radius of the secondcircle, and a third circle, wherein the third antenna is a center of thethird circle and the third distance is a radius of the third circle, anddetermine the intersection as the relative position of the first mobilerobot 100 a.

On the other hand, the second mobile robot 100 b of the presentinvention may determine the relative position of the first mobile robot100 a using only two antennas.

The second mobile robot 100 b may include a first UWB anchor and asecond UWB anchor included in the plurality of second modules atdifferent positions.

The first UWB anchor and the second UWB anchor may be disposed in thesecond mobile robot 100 b at a predetermined interval.

The first UWB anchor may include at least one antenna, and the secondUWB anchor may include at least one antenna.

The first module included in the first mobile robot 100 a may includeone UWB tag.

The control unit of the second mobile robot 100 b may determinedirection information (angle information) regarding where the firstmobile robot is located with respect to a forward direction of thesecond mobile robot, on the basis of a phase difference of signalsoutput from the one UWB tag and received through the first UWB anchorand the second UWB anchor.

For example, the control unit of the second mobile robot 100 b maydecide direction information (angle information) regarding where thefirst mobile robot 100 a is located with respect to the forwarddirection of the second mobile robot 100 b, using only two UWB anchorsother than three UWB anchors (or three antennas) in the aforementionedAoA manner.

To this end, the control unit of the second mobile robot 100 b mayreceive signals output from the UWB tag of the first mobile robot 100 athrough the first UWB anchor and the second UWB anchor, respectively.

If the signal received through the first UWB anchor is a first signaland the signal received through the second UWB anchor is a secondsignal, the control unit of the second mobile robot 100 b may determinea phase difference between the first signal and a second signal.

In addition, the control unit of the second mobile robot 100 b may knowinformation on a distance between the first UWB anchor and the secondUWB anchor in advance. The distance may be a value preset at the time ofmanufacture.

The control unit of the second mobile robot may calculate angleinformation regarding where the first mobile robot is located withrespect to a forward direction of the second mobile robot, based on thephase difference of the signals received in the first UWB anchor and thesecond UWB anchor, and determine direction information regarding wherethe first mobile robot is located with respect to the forward directionof the second mobile robot, based on the calculated angle information.

On the other hand, the control unit of the second mobile robot 100 b maycalculate distance information up to the first mobile robot based on atime between when the signals are transmitted and received between thefirst module (UWB tag) of the first mobile robot 100 a and the secondmodule (UWB anchors) of the second mobile robot 100 b. That is, thecontrol unit of the second mobile robot 100 b may determine the distanceinformation between the first mobile robot 100 a and the second mobilerobot 100 b using the ToF scheme.

The control unit of the second mobile robot 100 b may determine therelative position of the first mobile robot based on the calculateddistance information and the direction information.

The control unit of the second mobile robot 100 b may determine thedistance information through the ToF scheme and determine the directioninformation (or the angle information) through the AoA scheme.

The ToF scheme needs only one UWB tag and only one UWB anchor regardlessof the number while the AoA scheme needs one UWB tag and at least twoUWB anchors. Therefore, the first mobile robot 100 a of the presentinvention may be provided with one UWB tag and the second mobile robot100 b may be provided with at least two UWB anchors.

The description of the AoA method of recognizing the relative positionof the first mobile robot 100 a (in detail, the angle information(direction information related to the first mobile robot 100 a) usingthe two UWB anchors will be equally/similarly applied even to a case ofproviding two antennas in one UWB anchor of the second mobile robot 100b.

That is, when one UWB anchor has two antennas, the control unit of thesecond mobile robot 100 b may receive signals transmitted from the UWBtag of the first mobile robot 100 a via the two antennas, and determinedirection information (angle information) regarding where the firstmobile robot 100 a is located with respect to the forward direction ofthe second mobile robot 100 b, based on a phase difference of thesignals and a distance between the two antennas.

The present invention can provide a plurality of autonomous mobilerobots capable of accurately determining a relative position of a firstmobile robot while reducing costs.

The present invention can provide a plurality of autonomous mobilerobots, capable of improving accuracy and simultaneously reducing costsby calculating two accurate intersections using two UWB modules providedin a second mobile robot and determining whether a first mobile robot islocated at the front or at the rear using a plurality of antennas and ablocking member.

The present invention can provide a plurality of autonomous mobilerobots, capable of allowing seamless follow-up by recognizing relativepositions thereof irrespective of a communication state with a serverbecause relative positions of a first mobile robot and a second mobilerobot can be determined.

The functions/operations/control methods performed by the first mobilerobot 100 a disclosed herein may be performed by the control unit of thefirst mobile robot 100 a or the control unit of the second mobile robot100 b, and the functions/operations/control methods performed by thesecond mobile robot 100 b may be performed by the control unit of thesecond mobile robot 100 b or the control unit of the first mobile robot100 a.

In addition, the present invention may allow the second mobile robot 100b to determine the relative position of the first mobile robot 100 a.

Since the first mobile robot 100 a is the leading cleaner and the secondmobile robot 100 b is the following cleaner following up the firstmobile robot 100 b, the second mobile robot 100 b can more easily followthe first mobile robot 100 a by recognizing the relative position of thefirst mobile robot 100 a, which may result in reducing accuracy offollow-up and calculation time of the relative position.

Since the first mobile robot has to perform many calculations such asdetecting an obstacle according to a preset algorithm, creating mapinformation, determining a cleaning progress direction, and so on, suchcalculation load of the first mobile robot can be reduced as the secondmobile robot recognizes the relative position of the first mobile robot.

In this specification, description has been given of the example inwhich the second mobile robot 100 b recognizes the relative position ofthe first mobile robot 100 a, but the present invention is not limitedto this.

In general, when a plurality of autonomous mobile robots exists andtheir follow-up control is performed, the first mobile robot maydetermine the relative position of the second mobile robot so as toincrease accuracy and rapidity because the specification (Spec) ofcomponents provided in the first mobile robot as the leading robot isbetter than specification of components provided in the second mobilerobot.

Accordingly, the present invention may allow the first mobile robot 100a to determine the relative position of the second mobile robot 100 b.

To this end, the control unit of the second mobile robot 100 b maytransmit information (for example, distance information between the UWBtag and the plurality of antennas) calculated thereby to the firstmobile robot 100 a through the communication unit.

In this case, the control unit of the first mobile robot 100 a maydetermine the relative position of the second mobile robot 100 b (or therelative position of the first mobile robot 100 a with respect to thesecond mobile robot 100 b) based on the information received from thesecond mobile robot 100 b through the communication unit.

In order to determine (decide) the relative position of the secondmobile robot 100 b, the first mobile robot 100 a may include thosecomponents provided in the second mobile robot 100 b and the secondmobile robot 100 b may include those components provided in the firstmobile robot.

For example, the first mobile robot 100 a may be provided with a secondmodule (UWB anchor) having a plurality of antennas, and the secondmobile robot 100 b may be provided with a first module (UWB tag).

In this case, the control unit of the first mobile robot 100 a mayperform the functions/operations/control methods performed by thecontrol unit of the second mobile robot 100 b described in thisspecification, and the control unit of the second mobile robot 100 b mayperform the functions/operations/control methods performed by thecontrol unit of the first mobile robot 100 a.

Accordingly, the control unit of the first mobile robot 100 a candetermine the relative position of the second mobile robot 100 b throughthe functions/operations/control methods performed by the control unitof the second mobile robot 100 b.

When the first mobile robot 100 a determines the relative position ofthe second mobile robot 100 b, the first mobile robot 100 a may transmitthe determined relative position information of the second mobile robot100 b to the second mobile robot 100 b. Further, the second mobile robot100 b may determine the relative position of the first mobile robot 100a based on the received relative position information of the secondmobile robot.

Whether the first mobile robot 100 a determines the relative position ofthe second mobile robot 100 b or the second mobile robot 100 bdetermines the relative position of the first mobile robot 100 a may bedecided at the time of product production, and may be determined/changedby user setting.

FIGS. 11A, 11B, and 110 are alternative embodiments of follow-up controlbetween the first mobile robot and the second mobile robot in accordancewith the present invention. Hereinafter, a follow-up control between thefirst mobile robot and a mobile device will be described in detail.Here, the follow-up control disclosed herein means only that the mobiledevice follows a movement path of the first mobile robot.

Referring to FIG. 11A, the first mobile robot 100 a may control thefollow-up of a mobile device 200 by communicating with the mobile device200 instead of the second mobile robot.

Here, the mobile device 200 may not have a cleaning function, and may beany electronic device if it is provided with a driving function. Forexample, the mobile device 200 may include various types of homeappliances or other electronic devices, such as a dehumidifier, ahumidifier, an air purifier, an air conditioner, a smart TV, anartificial intelligent speaker, a digital photographing device, and thelike, with no limit.

In addition, the mobile device 200 may be any device if it is equippedwith a traveling function, and may not have a navigation function fordetecting an obstacle by itself or traveling up to a predetermineddestination.

The first mobile robot 100 a is a mobile robot having both thenavigation function and the obstacle detection function and can controlthe follow-up of the mobile device 200. The first mobile robot 100 a maybe a dry-type cleaner or a wet-type cleaner.

The first mobile robot 100 a and the mobile device 200 can communicatewith each other through a network (not shown), but may directlycommunicate with each other.

Here, the communication using the network is may be communication using,for example, WLAN, WPAN, Wi-Fi, Wi-Fi Direct, Digital Living NetworkAlliance (DLNA), Wireless Broadband (WiBro), World Interoperability forMicrowave Access (WiMAX), etc. The mutual direct communication may beperformed using, for example, UWB, Zigbee, Z-wave, Blue-Tooth, RFID, andInfrared Data Association (IrDA), and the like.

If the first mobile robot 100 a and the mobile device 200 are close toeach other, the mobile device 200 may be set to follow up the firstmobile robot 100 a through a manipulation in the first mobile robot 100a.

If the first mobile robot 100 a and the mobile device 200 are far awayfrom each other, although not shown, the mobile device 200 may be set tofollow up the first mobile robot 100 a through a manipulation in anexternal terminal 300 (see FIG. 5A).

Specifically, follow-up relationship between the first mobile robot 100a and the mobile device 200 may be established through networkcommunication with the external terminal 300 (see FIG. 5A). Here, theexternal terminal 300 is an electronic device capable of performingwired or wireless communication, and may be a tablet, a smart phone, anotebook computer, or the like. At least one application related tofollow-up control by the first mobile robot 100 a (hereinafter,‘follow-up related application’) may be installed in the externalterminal 300. The user may execute the follow-up related applicationinstalled in the external terminal 300 to select and register the mobiledevice 200 subjected to the follow-up control by the first mobile robot100 a. When the mobile device 200 subjected to the follow-up control isregistered, the external terminal may recognize product information ofthe mobile device, and such product information may be provided to thefirst mobile robot 100 a via the network.

The external terminal 300 may recognize the position of the first mobilerobot 100 a and the position of the registered mobile device 200 throughcommunication with the first mobile robot 100 a and the registeredmobile device 200. Afterwards, the first mobile robot 100 a may traveltoward the position of the registered mobile device 200 or theregistered mobile device 200 may travel toward the position of the firstmobile robot 100 a according to a control signal transmitted from theexternal terminal 300. When it is detected that the relative positionsof the first mobile robot 100 a and the registered mobile device 200 arewithin a predetermined following distance, the follow-up control for themobile device 200 by the first mobile robot 100 a is started. Afterthen, the follow-up control is performed by direct communication betweenthe first mobile robot 100 a and the mobile device 200 without theintervention of the external terminal 300.

The setting of the follow-up control may be released by the operation ofthe external terminal 300 or automatically terminated as the firstmobile robot 100 a and the mobile device 200 move away from thepredetermined following distance.

The user can change, add or remove the mobile device 200 to becontrolled by the first mobile robot 100 a by manipulating the firstmobile robot 100 a or the external terminal 300. For example, referringto FIG. 11B, the first mobile robot 100 a may perform the follow-upcontrol for at least one mobile device 200 of another cleaner 200 a or100 b, an air cleaner 200 b, a humidifier 200 c, and a dehumidifier 200d.

Generally, since the mobile device 200 is different from the firstmobile robot 100 a in its function, product size, and traveling ability,it is difficult for the mobile device 200 to follow up the movement pathof the mobile terminal 100 a as it is. For example, there may be anexceptional situation in which it is difficult for the mobile device 200to follow the movement path of the first mobile robot 100 a according toa geographical characteristic of a space, a size of an obstacle, and thelike. In consideration of such an exceptional situation, the mobiledevice 200 may travel or wait by omitting a part of the movement patheven if it recognizes the movement path of the first mobile robot 100 a.To this end, the first mobile robot 100 a may detect whether or not theexceptional situation occurs, and control the mobile device 200 to storedata corresponding to the movement path of the first mobile robot 100 ain a memory or the like. Then, depending on situations, the first mobilerobot 100 a may control the mobile device 200 to travel with deletingpart of the stored data or to wait in a stopped state.

FIG. 11C illustrates an example of a follow-up control between the firstmobile robot 100 a and the mobile device 200, for example, the airpurifier 200 b having a traveling function. The first mobile robot 100 aand the air purifier 200 b may include communication modules A and B fordetermining relative positions thereof, respectively. The communicationmodules A and B may be one of modules for emitting and receiving an IRsignal, an ultrasonic signal, a carrier frequency, or an impulse signal.The recognition of the relative positions through the communicationmodules A and B has been described above in detail, so a descriptionthereof will be omitted. The air purifier 200 b may receive travelinginformation corresponding to a traveling command (e.g., changes intraveling including a traveling direction and a traveling speed,traveling stop, etc.) from the first mobile robot 100 a, travelaccording to the received traveling information, and perform airpurification. Accordingly, the air purification may be performed in realtime with respect to a cleaning space in which the first mobile robot100 a operates. In addition, since the first mobile robot 100 a hasalready recognized the production information related to the mobiledevice 200, the first mobile robot 100 a can control the air purifier200 b to record the traveling information of the first mobile robot 100a, and travel with deleting part of the traveling information or wait ina stopped state.

The present invention described above can be implemented ascomputer-readable codes on a program-recorded medium. The computerreadable medium includes all kinds of recording devices in which datareadable by a computer system is stored. Examples of thecomputer-readable medium include a hard disk drive (HDD), a solid statedisk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, amagnetic tape, a floppy disk, an optical data storage device and thelike, and may also be implemented in the form of a carrier wave (e.g.,transmission over the Internet). In addition, the computer may alsoinclude the control unit 1800. The above detailed description should notbe limitedly construed in all aspects and should be considered asillustrative. The scope of the present invention should be determined byrational interpretation of the appended claims, and all changes withinthe scope of equivalents of the present invention are included in thescope of the present invention.

What is claimed is:
 1. A plurality of autonomous mobile robots,comprising: a first mobile robot including a first module fortransmitting and receiving an Ultra-Wideband (UWB) signal; and a secondmobile robot including a second module for transmitting and receivingthe UWB signal, wherein the second mobile robot is configured to followthe first mobile robot using the UWB signal, and the second moduleincluded in the second mobile robot comprises two antennas, wherein thetwo antennas comprise: a first antenna; and a second antenna located ata rear of the first antenna relative to a direction of movement of thesecond mobile robot, and the first antenna and the second antenna aredisposed with a blocking member for blocking the UWB signal interposedbetween the first antenna and the second antenna.
 2. The robots of claim1, wherein the second module included in the second mobile robotincludes a plurality of antennas, and wherein the second mobile robotincludes a control unit configured to determine a relative position ofthe first mobile robot based on the UWB signal received from the firstmobile robot through the plurality of antennas.
 3. The robots of claim1, wherein the two antennas are arranged on a same line.
 4. The robotsof claim 1, wherein the two antennas are disposed at outermost portionsof a main body of the second mobile robot to have a maximum spaceddistance between the two antennas on the main body.
 5. The robots ofclaim 4, wherein the main body of the second mobile robot blocks the UWBsignal.
 6. The robots of claim 1, wherein: the second module is a UWBanchor, the first mobile robot is provided with one UWB tag, and thesecond mobile robot is provided with two UWB anchors.
 7. The robots ofclaim 6, wherein the second mobile robot comprises a first UWB anchorand a second UWB anchor, and the first UWB anchor comprises: a firstantenna; a second antenna located at a rear of the first antennarelative to a direction of movement of the second mobile robot; and ablocking member interposed between the first antenna and the secondantenna to block the UWB signal.
 8. The robots of claim 7, wherein acontrol unit of the second mobile robot is configured to determine arelative position of the first mobile robot, based on the UWB signalreceived through the first and second UWB anchors and an antennareceiving the UWB signal of the first and second antennas.
 9. The robotsof claim 1, wherein a control unit of the second mobile robot isconfigured to control the second module to output the UWB signal, andwherein a control unit of the first mobile robot is configured to outputthe UWB signal through the first module, in response to reception of theUWB signal from the second module.
 10. The robots of claim 1, whereinthe second mobile robot comprises a first UWB anchor and a second UWBanchor included in a plurality of second modules and located atdifferent positions, wherein the first module included in the firstmobile robot includes a UWB tag, and wherein a control unit of thesecond mobile robot is configured to calculate a first distance betweenthe first UWB anchor and the UWB tag and a second distance between thesecond UWB anchor and the UWB tag, in response to the UWB signal outputfrom the UWB tag being received through the first and second UWBanchors.
 11. The robots of claim 10, wherein the control unit of thesecond mobile robot is further configured to determine two intersectionsbetween a first circle formed with a center located at the first UWBanchor and having a radius equal to the first distance, and a secondcircle formed with a center located at the second UWB anchor and havinga radius equal to the second distance.
 12. The robots of claim 1,wherein: the second mobile robot comprises a first UWB anchor and asecond UWB anchor corresponding to a plurality of second modules, thefirst UWB anchor comprises a first antenna, a second antenna and ablocking member, the blocking member is interposed between the firstantenna and the second antenna to block the UWB signal, and a controlunit of the second mobile robot is configured to determine one of twopositions determined by the plurality of second modules as a relativeposition of the first mobile robot, based on whether the UWB signal hasbeen received through the first antenna of the first UWB anchor orthrough the second antenna of the first UWB anchor.
 13. The robots ofclaim 12, wherein the control unit of the second mobile robot is furtherconfigured to: determine a position located at a front of the secondmobile robot relative to a direction of travel of the second mobilerobot as the relative position of the first mobile robot when the UWBsignal has been received through the one of the first antenna and thesecond antenna that is located at a front of the blocking member, anddetermine a position located at a rear of the second mobile robot as therelative position of the first mobile robot when the UWB signal has beenreceived through the one of the first antenna and the second antennathat is located at a rear of the blocking member.
 14. The robots ofclaim 1, wherein the second module included in the second mobile robotcomprises three antennas.
 15. The robots of claim 14, wherein the threeantennas are arranged in a triangular configuration.
 16. The robots ofclaim 1, wherein: the second mobile robot comprises a first UWB anchorand a second UWB anchor included in a plurality of second modules andlocated at different positions, the first module comprises one UWB tag,and a control unit of the second mobile robot is configured to determinea direction in which the first mobile robot is located with respect to afront of the second mobile robot based on a phase difference betweenrespective signals that are output from the one UWB tag and receivedthrough the first UWB anchor and output from the one UWB tag andreceived through the second UWB anchor.
 17. The robots of claim 16,wherein the control unit of the second mobile robot is furtherconfigured to: determine an angle at which the first mobile robot islocated with respect to the front of the second mobile robot based onthe phase difference between the respective signals received through thefirst UWB anchor and the second UWB anchor, and determine the directionin which the first mobile robot is located with respect to the front ofthe second mobile robot based on the determined angle information. 18.The robots of claim 16, wherein the control unit of the second mobilerobot is further configured to: determine a distance from the secondmobile robot to the first mobile robot based on a time between when asignal is transmitted and received between the first module and one ofthe plurality of second modules, and determine a relative position ofthe first mobile robot based on the determined distance and direction.